Results from four studies in multiple contexts drawing on different data sources provide full support for the proposition that Machiavellian employees prefer forming transactional psychological contracts (schemas of their employee–employer relationship that are economic in nature) and that such contracts mediate the relationship between Machiavellianism and supervisor-rated (a) organizational citizenship behaviors and (b) deviant behaviors, respectively. The authors’ research contributes to scholars’ understanding of the theoretical underpinnings of the relationship between Machiavellianism and contextual performance as well as to the psychological contracts literature by demonstrating that Machiavellianism influences contextual performance because it affects the manner in which employees construe their employment relationships.