This study reviews theories on striving for closure in adolescent networks related to trust issues of adolescents and further examines whether adolescents in mixed‐gender and single‐gender classes are different in striving for closure. Stochastic actor‐based models for network dynamics are applied to test our hypotheses based on longitudinal friendship nominations of 406 Taiwanese adolescents in mixed‐gender, all‐boy, and all‐girl classes. The results show that adolescents strive for closure through connections of friends' friends. Further, the results reveal that while the tendency toward closure is stronger for girls in mixed‐gender classes, such tendency toward closure is stronger in all‐boy classes than in all‐girl classes. Testing effects between types of classes supports the indications of variances in striving closure.