This study investigated the effect of organizational culture (supportive culture, innovation culture, goal culture and rule culture) on turnover intentions and whether this relationship was mediated by organizational practices of competencies development (training, functional rotation and individualized support) and affective commitment. The study sample consisted of 369 participants working in organizations based in Portugal. The results show that only goal culture positively and significantly affects the three dimensions of organizational practices of development competencies and affective commitment. The culture of support has a positive and significant effect on functional rotation, individualized support and affective commitment. The culture of innovation has a positive and significant effect on training. Supportive culture, goal culture and the dimensions of organizational practices of development competencies negatively and significantly affect exit intentions. The serial mediating effect of organizational practices of development competencies and affective commitment on the relationship between organizational culture (supportive culture and goal culture) and turnover intentions was proven. Organizational culture, especially supportive culture and goal culture, proved to be relevant in boosting the implementation of organizational practices of development competencies, boosting affective commitment and reducing turnover intentions.