Introduction. Integration of refugees and the members of the receiving communities is a two-way, dynamic and multidimensional process that includes members of both groups. Indicators of Integration Framework (Ager and Strang, 2008; Ndofor-Tah et al., 2019) defines four separate, but interlinked dimensions of refugee integration: Markers and Means (corresponding to the socioeconomic dimension), Social Connections (corresponding to the socio-psychological dimension), Facilitators, and Foundation. Each of these dimensions presents a series of integration challenges for refugees, and the success in overcoming them leads to the greater integration of the two groups. Socio-psychological dimension of integration is related to wellbeing of refugees and the members of the receiving communities, whereby both groups overcome challenges related to the positive intergroup relations – frequent and pleasant intergroup contact, high levels of social proximity, intertwining of the social networks, readiness to assist each other, positive intergroup attitudes, low levels of the perception of intergroup threat, etc. So far, research on socio-psychological integration mostly focused on describing and explaining the connections between various socio-psychological constructs believed to be relevant in the explanation of intergroup relations between the refugees and members of the receiving communities. Studies mostly focused on the experiences and perceptions of the receiving community members, with few studies exploring the socio-psychological integration in the refugee community. Correlation research mostly included intergroup attitudes (e.g. Ajduković et al., 2019; Croucamp et al., 2017; Pedersen et al., 2005), perception of intergroup threat (Schweitzer et al., 2005; Stephan et al., 2005; Sunhan et al., 2012), attitudes towards acculturation strategies (Geschke et al., 2010; Haase et al., 2019), intergroup contact (Barlow et al., 2012; De-Tezanos Pinto et al., 2017; Saab et al., 2017), social distance (Bruneau et al., 2017; Koc and Anderson, 2018), support of the receiving community members for the rights of refugees/asylum seekers and support for the integration policies (Verkuyten et al., 2018; Hartley and Pedersen, 2007), emotions and solidarity (Bračić, 2018; Pedersen and Thomas, 2013; Pawlicka et al., 2019; Verkuyten, 2004), political orientation and related personality traits such as right-wing authoritarianism and social dominance orientation (Anderson, 2016; Yitmen and Verkuyten, 2018). Experimental research mostly explored the perceptions of the receiving community members of the differences between groups of migrants (e.g. economic migrants and refugees) (Abeywickarma et al., 2018; Bansak et al., 2016; Gregurović et al., 2016), while the quasi-experimental methodology was used in studying effects of interventions on the changes in prejudicial attitudes towards refugees and asylum seekers (Berndsten et al., 2018; Cameron et al., 2007; Crowell, 2000). Research with refugees in the area of socio-psychological integration included the study of the concept of integration in refugees (Ager and Strang, 2004b), and wishes to return to their country (Di Saint Pierre et al., 2015; Wilson et al., 2017), while a smaller number of studies included intergroup contact (De Tezanos-Pinto et al., 2017; Haase et al., 2019; Saab et al., 2017), perception of attitudes of the receiving community towards own, refugee group (Cheah et al., 2013), experiences of discrimination (Bagci and Canpolat, 2019; Cheah et al., 2013; Di Saint Pierre et al., 2015; Parker, 2018; Wilson et al., 2017), and the role of social support in the process of adjustment to living in a new country (Anatawbi and Al Amad, 2019; Demir and Volkan, 2019; De Anstiss et al., 2019). These studies bring to attention various important connections between the indicators of sociopsychological integration, but also show some methodological shortages. Firstly, the concepts of socio-psychological dimension of integration and its indicators are not well defined. Secondly, the studies almost exclusively include members of the receiving community, thus ignoring integration as a two-way and dynamic process that includes interaction between the minority and majority group. With that, the challenge is to design the comparative indicators of socio-psychological integration for both the receiving community and refugees. Thirdly, the samples used in the aforementioned studies were mostly convenient samples which narrow the possibility of generalization of conclusions to the general public. Fourthly, the sociodemographic and socio-economic characteristics of the participants were included solely as control variables in the models, which contradicts the nature of dimensions of integration as interlinked and dependent on each other. Finally, the choice of predictors and criteria in these studies is not always consistent, with some constructs playing various roles in the models across studies. This doctoral thesis aimed to overcome detected methodological issues of previous research on the socio-psychological integration of refugees and receiving community. Research goal: The goal of this research was to compare the indicators of socio-psychological integration between refugees from Syria and members of the receiving community in Croatia and to explore the role of the perception of realistic and symbolic intergroup threat in refugees and members of the receiving community in the process of integration. To the best of our knowledge, no study has so far attempted to measure the same or comparable indicators of socio-psychological integration and to compare them between the groups. Furthermore, the perception of intergroup threat is a construct with a high potential for influence on the process of integration and has not yet been studied in the refugee communities. Perception of intergroup threat can be linked to the socio-economic and socio-psychological dimensions of integration alike, as well as the aspects of integration related to personal safety and stability, culture, religion and language. According to the Integrated threat theory (ITT, Stephan and Stephan, 2000), the perception of realistic intergroup threat is particularly related to personal and group resources such as employment, education, housing and personal safety. On the other hand, the perception of symbolic intergroup threat is related to the desire to maintain and protect one’s culture, customs, way of life and social identity. Perception of intergroup threat is closely related to the integration challenges of both refugees and receiving community members. Four research problems were defined: (1) To explore the theoretically expected differences in indicators of socio-psychological integration between refugees and members of the receiving community; (2) To determine whether socio-demographic characteristics, socio-economic indicators and socio-psychological indicators of integration predict the perception of realistic and symbolic intergroup threat in refugees from Syria in Croatia, and whether the sociopsychological indicators of integration add to the overall explanation of these criteria above and beyond socio-demographic characteristics and socio-economic indicators of integration; (3) To determine whether socio-demographic and socio-economic characteristics and sociopsychological indicators of integration, as well as the perception of the receiving community members of the impact of migration on the socio-economic situation in the country predict the perception of realistic and symbolic intergroup threat in members of the receiving community in Croatia; and (4) To test the mediation effect of the perception of intergroup threat in the relation of intergroup attitudes towards refugees and readiness of the receiving community members to assist refugees. Method: This research is a part of an international, interdisciplinary project Forced Displacement and Refugee-Host community Solidarity (FOCUS) funded by the European Commission from the Horizon 2020 Programme for Research and Innovation. A total of 600 members of the receiving community and 149 refugees from Syria participated in the study. The samples were gathered in three cities in Croatia that host the greatest number of refugees from Syria, thus increasing the probability of intergroup interaction – Zagreb, Karlovac and Sisak. Probabilistic sampling was used for the members of the receiving community who were approached using the Random Walk Technique. Refugees were approached using the Snowball Technique through the social networks of the researchers, interpreters of Arabic and non-governmental organizations that work with refugees. The participants provided answers to the survey questionnaire which contained a series of questions regarding the socio-demographic characteristics of the participants (for both groups), their socio-economic characteristics (for the members of the receiving community) or the indicators of their socio-economic integration (for the refugees), and the indicators of socio-psychological integration (for both groups). The survey questionnaires differed somewhat between the groups – some questions were posed identically for both groups with identical response options, a part of the questions was complementary between the groups, and a portion was exclusive to either group. For the socio-demographic characteristics of the members of the receiving community, age, sex, level of education, the importance of religion in their life, frequency of practising religious customs and political orientation were measured. For the refugees from Syria, age, sex, level of education, the importance of religion in their life, frequency of practising religious customs and the length of stay in Croatia were asked. The total monthly income of the household (in Croatian Kuna) was used as an indicator of the socio-economic status in the sample of the receiving community members. In the refugee sample, alongside the total monthly income of the household (in Kuna), proficiency in the Croatian language was measured as an indicator of socio-economic integration using three items on the proficiency in speaking, writing and reading Croatian. For the receiving community members, the perception of the socio-economic situation of refugees was measured using four items, and the perception of the impact of migration on the socio-economic situation in Croatia was measured using six items. In both groups, the indicators of socio-psychological integration were measured using identical or comparable measures. Intergroup attitudes towards the members of the other group were measured using six items (Intergroup attitudes scale, Ajduković et al., 2019). Perception of intergroup threat was measured using seven items, three for the perception of realistic and four for the perception of symbolic intergroup threat (Perception of threat scale, Ajduković et al., 2019). Intergroup contact was measured using ten items for five contexts of life, with participants estimating the quantity (frequency) and quality (degree of pleasantness) of intergroup contact for each context. The size of the social network of participants and the share of the members of the other group in their social networks were measured using six items. Social proximity was measured using five items (Social proximity scale, Ajduković et al., 2019). The frequency of experiences of discrimination was measured only in the sample of refugees from Syria, with a total of seven items, each relating to a different context of interaction with the members of the receiving community. Support of the members of the receiving community for the rights of refugees was measured using twelve items (Support for the rights of asylees scale, Ajduković et al., 2019), and their readiness to assist refugees was measured using four items (Readiness to assist asylees, Ajduković et al., 2019). Finally, in the receiving community sample, the participants estimated the degree to which the refugees were a part of the community they live in, in Croatia, using one item. Analysis: The analysis consisted of data preparation and preliminary analysis, analysis of characteristics of the participants in two samples using descriptive statistics, psychometric evaluation of scales including structural modelling, invariance testing and reliability testing, t-tests and chi-squares for comparison of the indicators of socio-psychological integration between the groups, hierarchical regression analysis for testing the prediction model of perception of intergroup threat in refugees, structural modelling for testing the prediction model of perception of intergroup threat in members of the receiving community, and structural modelling for testing the mediation effect of the perception of intergroup threat between the intergroup attitudes of the members of the receiving community towards the refugees and their readiness to assist refugees. Results: Refugees from Syria have shown a more positive view of the members of the receiving community than vice-versa in all indicators of socio-psychological integration. They presented more positive intergroup attitudes (t(434.350)= -24.846, p < .001, d = -1.844), lower levels of the perception of realistic (t(734) = 4.387, p < .001, d = 0.417), and symbolic intergroup threat (ts(736) = 10.751, p < .001, ds = 1.015), more frequent and more positive intergroup contact across all five contexts, a greater share of members of the receiving community in their social network than vice-versa (acquaintances – χ 2 (4, N = 741)= 467.510, p < .001; friends – χ 2 (4, N = 740) = 437.055, p < .001, persons to call for help – χ 2 (4, N = 744) = 413.838, p < .001), and a greater degree of social proximity (t(520.862)= -18.979, p < .001, d = -1.341). For refugees from Syria, two hierarchical regression analyses were conducted on multiply imputed datasets (m = 100) to determine significant predictors of (1) perception of realistic intergroup threat, and (2) perception of symbolic intergroup threat. For the perception of realistic intergroup threat, a prediction model included age, level of education, employment status, total monthly income of the household and Croatian language proficiency (step 1), quantity and quality of intergroup contact and frequency of experiences of discrimination (step 2). In step 1, only level of education was a significant predictor (b = 0.566, SE = 0.210, t = 2.682, p = .008), and the model explained around four percent of the total variance of the criterion (R 2 = .071, 95% CI [.012, .172], fmi = .07; Adj R 2 = .038, 95% CI [.001, .126], fmi = .127). In the second step, the level of education (b = 0.540, SE = 0.209, t = 2.582, p = .011) and the quality of intergroup contact with the members of the receiving community (b = -0.737, SE = 0.278, t = -2.654, p = .009) were significant predictors, and the model explained around seven percent of the total variance of the criterion (R 2 = .127, 95% CI [.041, .243], fmi = .068; Adj R 2 = .076, 95% CI [.012, .182], fmi = .111). Multivariate Wald test showed that the addition of the predictors in step 2 significantly increased the fit of the model to the collected data (d1 = 2,37, df1 = 3, df2 = 136, dfcom = 140, p = .073, riv = .178). For the perception of symbolic intergroup threat in refugees, a prediction model included age, level of education, frequency of practising religious customs and importance of religion in the life of the participant (step 1), and quantity and quality of intergroup contact and frequency of experiences of discrimination (step 2). In step 1 no predictor was significant, and the percentage of the explained variance of the criterion was very small, around three percent (R 2 = .029, 95% CI [.000, .109], fmi = .109). In the second step, the quality of the intergroup contact of refugee participants with the members of the receiving community was the sole significant predictor (b = -0.874, SE = 0.235, t = -3.718, p < .001), and the model explained around ten percent of the variance of the perception of symbolic intergroup threat in refugees (R 2 = .147, 95% CI [.054, .268], fmi = .073; Adj R 2 = .105, 95% CI [.027, .219], fmi = .101). Prediction models of perception of realistic and symbolic intergroup threat in members of the receiving community were tested using structural equation modelling. A very high number of missing values and a very small variability of the available data in the measures of quantity and quality of intergroup contact indicated that the contact the members of the receiving community have with the refugees is very rare and that the participants could not consistently estimate its quality. Therefore, intergroup contact was not included in the tested models. The model included the perception of realistic intergroup threat as a latent criterion, with two latent predictors – perception of the impact of migration on the socio-economic situation in the country, and support for the rights of refugees; and five single-item predictors – age, level of education, total monthly income of the household, political orientation and perception of the degree to which the refugees were a part of the community in which they live in, in Croatia (society membership). Covariances between item-level predictors and covariances between two indicators of the perception of the impact of migration were included in the model. Covariance between the latent variable of support for the rights of refugees and the item-level variable of perception of the degree to which the refugees are a part of the community was also allowed. This model presented a satisfying fit (χ 2 (79, N = 600) = 329.637, p < .001; CFI = .917; TLI = .896; RMSEA = .073, CI 90% [.065, .081]; SRMR = .071), and has in total explained 21% of the variance of the perception of realistic intergroup threat. Significant predictors were the level of education (β = -.110, b = -0.080, SE = 0.031, z = -2.578, p = .010, CI 95% [-.140, -.019]), total monthly income of the household of the participant (β = -.114, b = -0.022, SE = 0.009, z = -2.315, p = .021, CI 95% [-.040, -.003), political orientation (β = .217, b = 0.137, SE = 0.032, z = 4.257, p < .001, CI 95% [.074, .200]), and support for the rights of refugees (β = -.307, b = -0.290, SE = 0.052, z = -5.524, p < .001, CI 95% [-.392, -.187]). The prediction model for the perception of symbolic intergroup threat in receiving community members included the perception of symbolic intergroup threat as a latent criterion, one latent predictor – support for the rights of refugees; and six item-level predictors – age, level of education, political orientation, the importance of religion in the life of the participant, frequency of practising religious customs and the perception of the degree to which the refugees are a part of the community they live in Croatia (society membership). Covariances between item-level predictors were allowed, as well as the covariance between the support for the rights of refugees and the society membership. This model showed a good fit (χ 2 (42, N = 600) = 148.849, p < ,001; CFI = .955; TLI = .939; RMSEA = .065, CI 90% [.054 , .077]; SRMR = .046), and explained almost 38% of the variance of the perception of symbolic intergroup threat. Significant predictors were age (β = .105, b = 0.008, SE = 0.003, z = -2.700, p = .007, CI 95% [.002, .014]), political orientation (β = .152, b = 0.122, SE = 0.039, z = 3.111, p = .002, CI 95% [.045, .200]), support for the rights of refugees (β = -.518, b = -0.618, SE = 0.058, z = -10.564, p < ,001, CI 95% [-.732, -.503]), and the society membership (β = -.122, b = -0.141, SE = 0.056, z = -2.519, p = .012, CI 95% [-.205, -,031]). A model testing the mediation of the perception of realistic and symbolic threat in the prediction of the readiness to assist refugees based on intergroup attitudes showed a poor fit to the collected data. Modification indices indicated a need for multiple factor loadings of items which are theoretically measures of a single factor. Therefore, the changes in the model were not supported by the theory and previous empirical research and were not implemented in the model. Discussion: This research studied the indicators of socio-psychological integration in refugees from Syria and members of the receiving community in Croatia with special emphasis on the role of the perception of intergroup threat in both groups. It was shown that the refugees consistently perceive the receiving community in a more positive light than vice-versa. Refugees from Syria showed more positive attitudes towards the receiving community, a greater level of social proximity towards it, a greater share of receiving community members in their social circles, and more frequent and more positive intergroup contact than the receiving community members showed. Additionally, the refugees presented lower levels of perception of realistic and symbolic intergroup threat than did the receiving community members, though based on the Integrated threat theory, the refugees are expected to present higher levels of perception of the realistic intergroup threat than receiving community. In another, qualitative research conducted with refugees from Syria and the receiving community members in Croatia, the authors found strong narratives presenting the perception of realistic threat in the receiving community members, which was equally, if not more prominent than symbolic intergroup threat and often justified based on the macro-economic situation in the country (Kiralj and Ajduković, in press). Members of the receiving community did show less frequent intergroup contact with the refugees from Syria, as expected, but this contact was much rarer than expected. Although the sampling of the receiving community was probabilistic in three cities that host the greatest number of refugees, it seems that the very small size of the refugee population lead to the low likelihood of intergroup contact. Some research shows the effect of imagined contact on the reduction of prejudice and pro-social behaviour (Miles and Crisp, 2013), and the effect of spontaneous imagining of pleasant contact on attitudes and social distance towards the members of the other group (Stathi et al., 2019). It is possible that in the absence of real-world intergroup contact, techniques like imagining pleasant contact can positively influence indicators of sociopsychological integration and lead to desired outcomes, such as the reduction of intergroup threat and promoting positive intergroup attitudes. Refugees with higher levels of education and those who estimated the quality of their contact with the members of the receiving group as more negative have also showed higher perception of realistic intergroup threat. Those refugees who estimated the quality of intergroup contact as more negative also reported higher perception of symbolic intergroup threat. These findings add to other empirical findings on the importance of intergroup contact in the mechanism of intergroup threat. Very low percentage of explained variance of perception of realistic and symbolic threat indicates that constructs predicting the perception of threat in the receiving community might not be adequate for the explanation of the phenomena in the refugee community. Members of the receiving community who had lower levels of education, lower total monthly income of the household, those who were right-wing oriented and those who showed lesser support for the rights of the refugees presented higher levels of perception of realistic intergroup threat. Similarly, those who were older, right-wing politically oriented, who perceived the refugees to be a part of the society to a lesser extent and those who showed lesser support for the rights of refugees, presented higher levels of the perception of symbolic intergroup threat. These prediction models explained a fair amount of the variance of the criteria and validated previous empirical findings in the field. Conclusion:Integration of refugees and receiving communities is a multidimensional, dynamic and complex phenomenon that should be studied in both groups simultaneously. This study adds to the existing literature on the integration process, socio-psychological integration and intergroup relations by taking into account the interplay of the socio-economic and socio-psychological dimensions of integration. By including the members of both groups and asking the same or comparable questions, this research is the first to our knowledge to study the similarities and differences between the two groups in the indicators of socio-psychological integration and adds to the body of research on the perception of intergroup threat by studying the predictors of intergroup threat in receiving community members and in refugees from Syria.