We examined whether parent engagement in parent training (PT) differed based on PT format (parent group-based with video versus mastery-based individual coaching with child) in an economically disadvantaged sample of families seeking behavioral treatment for their preschool children in an urban mental health clinic. Parents (N = 159; 76.1% mothers, 69.8% African American, 73% low-income) were randomized to one of two interventions, Chicago Parent Program (parent group + video; CPP) or Parent–Child Interaction Therapy (individualized mastery-based coaching; PCIT). Parent engagement indicators compared were PT attendance and completion rates, participation quality, and parent satisfaction. Risk factors predictive of PT attrition (parent depression, psychosocial adversity, child behavior problem severity, length of wait time to start PT) were also compared to determine whether they were more likely to affect engagement in one PT format versus the other. No significant differences were found in PT attendance or completion rates by format. Clinicians rated parents’ engagement higher in PCIT than in CPP while satisfaction with PT was rated higher by parents in CPP compared to PCIT. Never attending PT was associated with more psychosocial adversity and externalizing behavior problems for CPP and with higher baseline depression for PCIT. Parents with more psychosocial adversities and higher baseline depression were less likely to complete PCIT. None of the risk factors differentiated CPP completers from non-completers. Delay to treatment start was longer for PCIT than CPP. Strengths and limitations of each PT format are discussed as they relate to the needs and realities of families living in urban poverty.