Purpose: Drawing on social exchange theory and the expectancy–value model, this study has two objectives. First, it sought to explore the mediating role of nurses’ self-concept and affective commitment between perceived organizational support (POS) and three different targets (organization, co-workers and patients) of organizational citizenship behavior (OCB). Second, it aimed to develop a better understanding of how nurses´ self-concept and affective commitment mediate the influence of POS on OCB directed toward different targets through sequential mediation. Design/methodology/approach: A cross-sectional study was conducted with 229 nurses. This sample was representative of the nursing population based on several demographic characteristics. Data analysis was performed using partial least squares analysis. Findings: The study revealed that nurses´ self-concept plays a mediating role between POS and OCB directed toward the organization, co-workers and patients, while affective commitment has a mediating effect between POS and OCB directed toward the organization and co-workers. Finally, the indirect influence of POS on OCB through nurses´ self-concept and affective commitment was significant only at the organizational level. Originality/value: This study contributes to the extant literature by identifying the mediating role of nurses´ self-concept among social exchange constructs such as POS, affective commitment and OCB directed toward different targets.