The primary aim of the research was to determine the quality of cooperation between primary school teachers in regular classes and their fellow teachers in extended day program, as partners in the teaching profession. The second goal was to identify all aspects of their cooperation and to examine whether there are statistically significant differences in the level of cooperation, the fulfilment of basic psychological needs, as well as the level of job and life satisfaction of these two groups of teachers. The final objective was to determine the predictive value of the quality of teacher cooperation and the level of satisfaction of basic psychological needs at work in explaining the level of job and life satisfaction, as well as the mediating role of basic psychological needs in the relationship between the quality of cooperation and the job and life satisfaction of both groups of teachers. The research was conducted on a sample of primary schools teachers in the City of Zagreb schools that have an organized extended day program. 319 teachers participated in the research, of which 52% were teachers in regular classes and 48% teachers in extended day program. Data was collected by using: 1) Scale of the quality of teacher cooperation (ger. Skalen zur Schulqualität) (Gerecht, Steinert, Klieme, & Döbrich, 2007), 2) Job Diagnostic Survey (Hackman & Oldham, 1974), 3) Satisfaction with Life Scale (Diener, Emmons, Larsen, & Griffin, 1985) and 4) Work Related Basic Need Satisfaction Scale (Van den Broeck et al., 2010). The results showed that teachers in extended day program are more satisfied with the quality of cooperation, while teachers in regular classes are more satisfied with the frequency of cooperation. Furthermore, the results indicate that there is no statistically significant difference in the satisfaction of basic psychological needs at work between teachers in regular classes and teachers in extended program. The research confirmed that all forms of teacher cooperation and satisfaction of basic psychological needs at work are significant positive predictors of job and life satisfaction in both groups of teachers. The obtained results suggest that three dimensions of teacher cooperation (quality of teaching cooperation, communication in the school collective and school cooperation), as well as fulfilment of the psychological need for autonomy are statistically significant predictors of job satisfaction among teachers in regular classes, while two dimensions of teacher cooperation (quality of the communication in the school collective and the quality of school cooperation), as well as the satisfaction of psychological needs for relatedness and autonomy are significant predictors of teacher job satisfaction in extended day program. Furthermore, it was determined that satisfaction of the psychological need for competence and psychological need for autonomy are statistically significant predictors of life satisfaction of teachers in regular classes, while the quality of teacher cooperation did not prove to be a significant predictor. For teachers in extended day program, the satisfaction of all three basic psychological needs at work is a significant predictor of life satisfaction. The results of the research indicate that the psychological need for autonomy is a statistically significant mediating variable between the quality of cooperation and job satisfaction among teachers in regular classes, and the psychological need for relatedness and the psychological need for autonomy were confirmed as statistically significant mediating variables between the quality of cooperation and job satisfaction among teachers in the extended day program. Furthermore, the results confirmed that all three basic psychological needs are statistically significant mediating variables between the quality of cooperation and life satisfaction in both groups of teachers. The results of the research can contribute to a better understanding of the connection of the quality of cooperation and the psychological needs of classroom teachers in regular classes and teachers in extended day program with their work and life satisfaction. The results can serve as guidelines for school managers for a more effective organization of educational work with the aim of fostering conditions for better cooperation between teachers and better satisfaction of their psychological needs at work, and consequently they could contribute to a higher level of job and life satisfaction of teachers.