This study identified and described adolescents' exclusion rules and how they were related to their real world exclusionary behaviours. Adolescents (N=682) were asked to provide (a) an account and rationale for excluding a peer who wanted to join their group; and (b) general rules for when exclusion was fair. A content analysis of the narratives suggested seven rejection rules that were somewhat consistent with adolescents' reported acts of social exclusion: (a) unattractive; (b) punishment; (c) dangerous; (d) group loyalty; (e) benevolent protection; (f) unqualified; and (g) never. The data demonstrated that adolescent peer groups provide fertile soil for cultivating and performing moral exclusion. Both theoretical and applied implications of the findings are discussed.