Research examining the effect of behavioral parenting interventions, such as parent–child interaction therapy (PCIT), on parent and child imitation is limited despite known benefits to early child development. We examined the effect of a brief, home-based adaptation of PCIT, the Infant Behavior Program (IBP), on changes in observed frequency of parent and infant imitation, moderating effects of parent language (English, Spanish), and mediational effects of parent and infant imitation on the effect of intervention on infant behavior problems. Participants were 60 12- to 15-month-olds with elevated behavior problems and their primary caregiver, all of which were mothers. Parent–infant dyads were randomly assigned to receive either the IBP or standard pediatric primary care. Parents receiving the IBP demonstrated significantly higher rates of observed imitation at postintervention and at the 3-month follow-up compared to those receiving standard care, and the effect at postintervention was stronger for English-speaking than for Spanish-speaking families. Although the IBP did not directly affect changes in infant imitation at postintervention or the 3-month follow-up, rates of infant imitation increased significantly for those who received the IBP at the 6-month follow-up. Additionally, moderation results suggested that the IBP led to improvements in infant imitation at post for Spanish-speaking families but not for English-speaking families. There were no significant mediational effects of parent or infant imitation. Future research is needed to examine the impact of increases in imitation on other aspects of child development, such as social–cognitive and language abilities, and to examine how cultural factors may play a role in individual differences in imitation.