Concurrent associations between parenting behaviors and youth depression are well established. A smaller body of work has demonstrated longitudinal associations between aspects of parenting and youth risk for depression; however, this limited longitudinal work has predominantly relied upon self- and parent-report questionnaire measures and is thus affected by biases related to retrospective recall and common method variance. The present study used behavioral observation measures of parenting and clinical interview measures of youth depression to examine prospective relationships between observed parental support, responsiveness, criticism, and conflict and youths’ onset of a depressive episode in a 3-year longitudinal design. Participants included 585 community youth age 8–16 (M = 11.92, SD = 2.39, 56.6% female) and a participating caregiver. Parental behavior was coded by trained observers in the context of a 5-min conflict resolution discussion at the baseline assessment. Youth onset of depression was subsequently assessed every 6 months for a period of 3 years using the Schedule for Affective Disorders and Schizophrenia for School Aged Children (KSADS) to ascertain whether youth experienced onset of depressive episode over the follow-up. Logistic regression analyses indicated that greater parental conflict at baseline predicted higher odds of youth experiencing a depressive onset across the 3-year follow up period, even after controlling for youth and caregiver history of depression at baseline. Findings suggest that parental conflict is particularly influential in youth vulnerability to depression.