The aim of this research was to examine the role of executive functions (inhibitory control and decision-making in complex and unclear situations) in inmates' adjustment to prison conditions and their mental health (anxiety and depression) as a form of that adjustment. A total of 104 prisoners who were, at the time of the research, in one of the penal institutions in the Republic of Croatia participated in the research. Executive functions were measured with behavioral tasks available on the Psychology Experiment Building Language (PEBL; Mueller and Piper, 2014) computer platform. Adaptation was measured with two questionnaires. Adjustment to prison conditions was measured by the Prison Adjustment Questionnaire (PAQ; Wright, 1985), and mental health difficulties by the Patient Health Questionnaire (PHQ-4; Kroenke et al., 2009). One-way analysis of variance (ANOVA) was used to examine the differences between sociodemographic variables in the investigated variables. The partial squared eta (ηp2) was used to measure the effect size. Finally, partial correlation analysis was used in the research. The results of the partial correlation analysis did not show a correlation between the questionnaire and the behavioral tasks, which did not confirm any of the hypotheses. Nevertheless, the results contributed to significant knowledge related to the influence of sociodemographic variables on adaptation to prison conditions.