Perinatal depression prevention trials have rarely examined proximal outcomes that may be relevant for understanding long-term risk for depression. The Mothers and Babies (MB) Course is a cognitive-behavioral depression prevention intervention, which has been shown to prevent depressive symptoms among at-risk perinatal women of color. This study examined intervention impact on three proximal outcomes that are theoretically linked with the intervention's model of change and have been empirically linked with risk for depression: mood regulation expectancies, perceived social support, and coping. The study used data from a randomized intervention trial of the MB Course with 78 low-income, predominantly African-American perinatal women enrolled at one of four home visitation programs in Baltimore City. Mood regulation expectancies, perceived social support, and coping were assessed with self-report instruments at baseline, post-intervention, and 3- and 6-month follow-ups. The intervention group experienced 16 % greater growth in mood regulation from baseline to 6-month follow-up compared to the usual care group, suggesting a prevention effect. The pattern of findings was similar, although not statistically significant, for social support. Contrary to prediction, the control group experienced less growth in avoidant coping than the intervention group. Findings indicate the MB Course enhances mood regulation, which may facilitate prevention of depression over time. Assessment of intervention effects on proximal outcomes is beneficial for understanding how interventions may enhance protective factors relevant to successful long-term outcomes.