This study evaluated a comprehensive model of factors associated with internalizing problems (IP) in early childhood, hypothesizing direct, mediated, and moderated pathways linking child temperamental inhibition, maternal overcontrol and rejection, and contextual stressors to IP. In a novel approach, three samples were integrated to form a large sample (N = 500) of Canadian children (2–6 years; M = 3.95 years; SD = .80). Items tapping into the same constructs across samples were used to create parallel measures of inhibited temperament, maternal positive, critical, and punitive parenting, maternal negative emotionality, family socioeconomic and structural stressors, and child's IP. Multiple-groups structural equation modeling indicated that associations were invariant across samples and did not differ for boys and girls. Child inhibition, less positive and more critical parenting, maternal negative emotionality, and family socioeconomic disadvantage were found to have direct associations with IP. In addition, maternal negative emotionality was associated with IP through more critical parenting, and both maternal negative emotionality and socioeconomic stress were associated with IP through less positive parenting. Results highlight the multiple independent and cumulative risk factors for early IP and demonstrate the power of integrating data across developmental studies.