Despite epidemiological reports indicating that individuals with social anxiety disorder (SAD) are at heightened risk for cannabis use disorders (CUD), there is a dearth of research investigating the mechanisms underlying the nature of this co-occurrence. The present study examined the role of a well-established risk factor for cannabis use, peer influence, on the relationship between symptoms of SAD and CUD in a non-referred sample (N = 123). Lifetime symptoms of SAD and CUD were assessed using a structured diagnostic interview. SAD symptoms were significantly correlated with CUD symptoms and this relationship was moderated by peer use of both alcohol and cannabis. Further, a gender effect indicated that the relationship between symptoms of SAD and CUD occurred only in women. Implications of these novel findings are discussed.