The current study focused on processes underlying Cuban students' academic performance. Using path analyses, the model examined the relations between family relationships and academic performance mediated by belongingness and moderated by sex differences among Cuban medical students (N = 613; M age = 21.39, SD = 2.05). Findings indicated that improved family relationships significantly predicted increased belongingness to the field of medicine for both male and female students. The relation between belongingness and academic performance was only significant for male students. Thus, improved family relationships informed academic performance via belongingness for male medical students.