The aim of this study was to identify factors that promote and impede other-sex (OS) friendships in adolescent girls.A qualitative study conducted with 20 adolescent girls recruited in public places in Tehran, Iran. Information was collected through semi-structured interviews and coded via the conventional qualitative content analysis approach.Four factors were identified that appeared to promote entry into OS friendships. These factors include (a) a poor understanding of perceived risks, (b) weak religious beliefs, (c) processes of identity formation, and (d) low self-esteem. In addition, six factors appeared to impede entry into these friendships: (a) self-confidence, (b) prioritizing education, (c) maintaining particular entertainment preferences, (d) awareness of prior unpleasant experiences with boys, (e) having strong religious convictions, and (f) shaming from significant others.These findings provide unique insights into the factors that stem from different levels of social complexity, which affect participation in a fundamental form of human experience.