A growing number of studies demonstrate associations among false-belief understanding (FBU), executive function (EF), and social competence. This study extends previous studies by exploring longitudinal associations among FBU and its correlates within a low-income sample of preschoolers attending Head Start. Sixty-eight children (time 1 mean age = 5 years 2 months) were assessed over their preschool and kindergarten years. Results indicated bidirectional relations between FBU and social competence; FBU in preschool was positively associated with social competence in kindergarten and social competence in preschool was positively associated with FBU in kindergarten. Preschool EF was positively associated with social competence both in preschool and kindergarten and with FBU in preschool. Mediation analyses suggest that the bidirectional longitudinal link between FBU and social competence was independent of EF. These findings extend the FBU literature by examining its development and correlates in early childhood. Implications for future research and practice are discussed. (Contains 7 tables and 2 figures.)