Mental health is defined as „well-being in which an individual realizes his own abilities, can cope with everyday life stresses and contribute to his community through his productive work“ (WHO, 2004). The aim of this study was to examine positive mental health in young people during the period of transition from adolescence to adulthood and some of its determinants such as sociodemographic characteristics, characteristics of emerging adulthood, religiosity and self-esteem. An online survey was conducted on a sample of 232 participants, age 18 to 29, that, according to the theory, belong to the emerging adulthood, transition period between adolescence and adulthood. The average age of the participants was 22.63 years. Participants completed Mental Health Continuum (MHC-SF; Keyes, 2005), Inventory of the Dimension of Emerging Adulthood (IDEA; Reifman et al., 2007), Questionnaire of Religiosity (Ljubotina, 2004), Scale of Self-Esteem Scale (RSE; Rosenberg, 1965) and a questionnaire on sociodemographic characteristics. The results showed that young people have moderately mental health during the transition from adolescence to adulthood, with no significant difference in the levels of mental health between young man and women. Significant predictors of positive mental health in young people are time of instability / negativity, (dimension of emerging adulthood) religiosity and self-esteem, which explained 53.0% of the variance of mental health. Lower instability/ negativity and higher religiosity and self-esteem predict higher mental health of young people in the transition between adolescence and adulthood.