The sibling relationship represents a unique bond characterized by a high degree of closeness and intimacy, which fosters teaching and learning. Two studies investigated associations between sibling-directed teaching, imitation as a learning strategy, and learner involvement during a semi-structured, video-taped construction task. Study 1 also examined associations with the teacher's Theory of Mind (ToM) abilities; Study 2 focused on associations with birth order and sibling relationship quality. In both studies, siblings ranged from preschool-age to the cusp of middle childhood (Study 1 n = 61; Study 2 n = 72). Findings across both studies indicated that learners engaged in significantly more nonverbal than verbal imitation and imitation was predominately immediate and not deferred. Teachers responded to both verbal and nonverbal learner imitation positively, corrected, or did not respond. In Study 1, learner task involvement was predicted by learner age and nonverbal imitation, while teaching strategies that were positively related to the teacher's ToM abilities were associated with learner imitation. In Study 2, younger siblings' reports of a positive sibling relationship were significantly associated with learner imitation. Birth order differences were only evident for younger (but not older) sibling learner imitation and task involvement. Findings are discussed in light of relationships and social constructivist theories of development.