Family factors are associated with suicidal behavior in youth, but little is known about how the joint influence of multiple family factors prospectively predicts onsets of suicidal ideation (SI) in adolescence, a developmental period characterized by increases in SI and risk for suicide. This study investigated whether parent history of SI interacted with either positive or negative parent-child relationship quality to longitudinally predict time to SI onsets during the transition into and across adolescence. Specifically, we used a longitudinal, multi-wave design and survival analyses to examine whether the interaction between these family factors prospectively predicted time to emergence of SI onsets (assessed at 6 month intervals over 3 years) in a community sample of youth ages 8 to 15 (N = 238; 57% girls). Results supported an interaction effect, such that more negative relationship quality with parents predicted earlier emergence of SI among those youth whose parents had no history of SI. However, negative parent relationship quality did not amplify risk among youth with parent history of SI; all youth with a parent history of SI were more likely to experience earlier emergence of SI regardless of level of negative relationship quality. Findings did not support an interaction between low levels of parent-child positive relationship quality and parent history of ideation. Implications for the role of family factors in the etiology and prevention of SI are discussed.