Drawing on evolutionary psychology, social exchange styles were conceptualized in terms of two dimensions of individual differences in approaching exchange relationships: Benefit-seeking and cost-vigilance. In Study 1, a principal components analysis of the Social Exchange Styles Questionnaire (SESQ) in 156 undergraduates confirmed the presence of two dimensions that were very similar to the expected dimensions: Equitable alliance building (EAB) and vigilant alliance management (VAM). The SESQ scales showed good internal consistency and construct validity. Multiple regressions confirmed that social exchange styles were distinct from other personality variables. In Study 2, multilevel modelling conducted on 45 small work groups demonstrated that EAB positively predicted members' subjective performance, while VAM positively predicted objective performance. Theoretical questions and future research directions are discussed. Copyright © 2010 John Wiley & Sons, Ltd.