Relationships between patterns of extradyadic involvement (EDI) and adult attachment were examined separately with undergraduates and community adults reporting prior EDI. Those with fearful or preoccupied styles reported more intimacy motivations for EDI, and undergraduates with these styles also reported more self-esteem motivations. Conversely, those with a dismissive style reported more autonomy motivations for EDI. Those with a fearful attachment style reported ambivalence about intimacy in the EDI. Fearful and preoccupied undergraduates and community males reported a more obsessive extradyadic relationship. However, dismissive individuals did not report more casual EDI. Gender effects also emerged, with females reporting more intimacy motivations than males, and undergraduate males reporting more casual EDI than undergraduate females. In the undergraduate sample, dismissive males had the most extradyadic partners over the prior 2 years relative to all other groups, and preoccupied females reported more partners than secure females. Clinical implications of these findings are discussed.