The aim of this paper was to examine the contribution of mental health and risky behaviors in relation of certain life opportunities (exposure to social networks, frequency of consumption of online pornography and live intimate experiences), within The opportunity theory, and frequency of different forms of adolescent sexting, through the theoretical model of adolescent sexting (MSA), constructed for the purposes of this research. Sexting is broadly defined as sending, receiving or forwarding sexually suggestive or explicit content (text messages, photos, video calls) via mobile phone or the Internet and is divided into problematic forms (forwarding content and sexting with reduced consent) and non-problematic forms (receiving and sending sexting content). The opportunity theory, which is widely applicable and verified to explain various risky behaviors, was used as a theoretical framework, but in a modified form. Namely, it was assumed that certain life opportunities contribute to the occurrence and frequency of all types of behavior, not only risky, and that the relationship between life opportunities and ultimate behavior is not simple or unequivocal, but it can be indeed at least partially mediated by some factors. The main assumptions were therefore that there is a significant contribution of certain life opportunities in the explanation of all forms of sexting, while the relationship between certain life opportunities and the frequency of problematic forms of sexting is mediated by the intensity of internalized and externalized mental health difficulties and risky behaviors both live and online, which was not assumed for the frequency of non-problematic sexting. An exploratory problem was also set – to examine the expression of certain life opportunities, internalized and externalized mental health difficulties, and the frequency of non-problematic (receiving and sending content) and problematic sexting (with reduced consent and forwarding content) on the entire sample, with regard to the measured demographic characteristics of the participants. The data was collected from the database of the national research project "Social network experiences and mental health of young people", which was carried out in 2019 by the Child and Youth Protection Center of Zagreb in cooperation with the Zagreb City Health Office and the Society for Communication and Media Culture. The sampling procedure was carried out in accordance with the proportionality and representativeness of the age groups of the first and third grades of secondary schools, based on an insight into the available statistical indicators of the National Bureau of Statistics (2016/2017 and 2017/2018) and pedagogical standards of the number of students. In doing so, the ratios of gender and gymnasium/vocational schools in five cities (Zagreb, Rijeka, Osijek, Dubrovnik and Split) were taken into account, and the schools were chosen by random selection. All 24 contacted schools accepted to participate, as well as students within the classes. The final number of participants, after arranging the base, was 1653. The participants are approximately equal in terms of sex/gender, grade and type of school they attend. Using the paper-pencil method, the participants first filled out Beck's inventories in the edition of Naklada Slap, after which they filled out the remaining (larger) part using tablets provided by the researchers via the Google forms platform. A unique code, that had to include letters and at least two numbers, was used to match the answers of each participant on the tablet and on paper. Some existing instruments were used in their original form (Beck's inventories), in their modified form (Multidimensional Facebook Intensity Scale, - MFIS; Orosz, Tóth-Király and Bőthe, 2016 and Sexting Behaviors Questionnaire - SBQ; Morelli et al., 2016), some in abbreviated form (Index of adolescent sexual behavior; Hennessy et al., 2008). Other variables were measured with individual particles and newly constructed scales for the purposes of this research, all with satisfactory, moderate to high, reliability coefficients of the internal consistency type. Simple parametric tests were used for statistical processing in the exploratory problem. Considering the demographic characteristics, it is shown that young men sext more often in all forms compared to girls, and young people of homosexual orientation more often sext problematically compared to youth of other sexual orientations. Third-grade students receive sexting content more often than first-grade students, and vocational school students sext more often non-problematically, but not problematically, compared to gymnasium students. The frequency of sexting does not appear to be related to the size of the city they spent most of their lives in, and with regard to socio-economic status, the highest involvement in sexting is among participants at the extreme ends of the continuum – those extremely above and below average. Four models were created to verify the hypotheses set forth below. All models have the same predictor variables (certain life opportunities). The criterion is the frequency of sexting – in two models of problematic sexting (frequency of forwarding content and sexting with reduced consent), and in two models of non-problematic sexting (frequency of sending and receiving content). Therefore, one model was developed for both problematic and non-problematic sexting for checking the mediation of mental health difficulties, and one model for both problematic and non-problematic sexting for checking the mediation of risky behaviors, live and online. The results only partially confirm the set hypotheses. Without the introduction of mediators, it is shown that some, although not all, measured life opportunities predict the frequency of sexting, both problematic and non-problematic, which would be expected within the framework of The (original) Opportunity theory. Also, considering the different relationships between the frequency of problematic and non-problematic forms of sexting with some key variables, it seems that the division of sexting into these two categories is justified. However, by further examining the dynamics of the presented relationships through the introduction of mediator variables, different conclusions could be reached. When introduced in the models as mediating variables, the level of disruptive behavior as an externalized difficulty, and risk behaviors, live and online, at least partially reduce, and in some cases even nullify, the significance of the found relationships of life opportunities and frequency of sexting. Mediators are also significant for non-problematic, and not only for problematic forms of sexting, which was not assumed. This research therefore shows that a modified version of The opportunity theory, which takes into account the dynamics of the relationship between certain life opportunities and ultimate behavior, explains the frequency of youth sexting in more detail and depth than the original theory. Also, by analyzing the relationship between the frequency of different forms of sexting among youth and other variables, the question of the justification of dividing sexting with regard to its (non)problematic nature is raised. Namely, it seems that, at least with regard to these relationships, even those forms of sexting that are assumed to be unproblematic, can be considered (approximately) as problematic as forwarding and sexting with reduced consent. These findings unclench the space for further verification of the modified Opportunity theory, both for youth sexting within the framework of the Adolescent Sexting Model, and for numerous other behaviors previously explained through the original theory. They also continue a very lively professional-scientific debate on the problematic and risky nature of all or certain forms of sexting, emphasizing the crucial importance of starting theoretical frameworks, defining and operationalizing key concepts. They focus future research on overcoming methodological challenges and verifying the obtained knowledge through longitudinal or cross-sequential designs, which is primarily important in a practical sense. To clinicians, they present youth sexting as an important topic in work with adolescents, especially certain groups of adolescents, and to prevention experts, they provide the progress in developing necessary theoretical frameworks and empirical findings for future planning of successful interventions, their implementation and evaluation.