The role of anxiety/depression in the progression of youth externalizing problems to future high risk behaviors has been disputed in the literature. Mixed support exists for a multiple problem hypothesis (i.e., co-occurring anxiety/depression leads to more high risk behaviors) and a protective hypothesis (i.e., anxiety/depression buffers this progression). The present study compared these two hypotheses in a sample of 124 African-American single mother families by examining mother report of externalizing problems and anxiety/depression at an initial timepoint and youth report of high risk behaviors fifteen months later. Results support the multiple problem hypothesis: In the context of high levels of externalizing problems, high levels of anxiety/depression were associated with more youth engaging in high risk behavior across the 15 month follow-up than were low levels of anxiety/depression. The findings suggest it is important to consider multiple domains of youth problem behaviors to conceptualize and prevent high risk behaviors.