We investigated how and when individuals transform existing cross-group interactions into more positive attitudes towards outgroups. Specifically focusing on the context of Syrian immigration to Turkey, we examined whether native children’s cross-group friendship self-efficacy beliefs—the perception of their abilities about building successful cross-group interactions—moderated the direct and indirect associations between cross-group friendship quantity (measured by the number of Syrian friends), cross-group friendship positivity and negativity, and attitudinal outcomes (outgroup attitudes, intergroup anxiety, and social distance). Analyses of correlational data (5th graders, N = 746) demonstrated that direct and indirect (through cross-group friendship positivity) associations between cross-group friendship quantity and positive intergroup outcomes were stronger among children who held greater self-efficacy beliefs. Importantly, quantity of such friendships was related to more negative intergroup outcomes through negative contact experiences among children who reported lower self-efficacy beliefs. Theoretical implications of the findings and possible interventions targeting self-efficacy beliefs in intergroup contact strategies were discussed.