Adopting the theoretical framework of the minimalist program, this study of syntactic limitations on complement configuration investigates the link between thematic external arguments and case. Using evidence from pronominal, psychological experiencer, and inalienable constructions, it argues that both accusative and dative are structural cases in French and that this duality is reflected in a parallel limit on argument projection. Larson’s single complement hypothesis, which allows a maximum of two internal arguments, provides the theoretical justification for this proposal. The testing ground for the binary hypothesis is a group of nonthematic subject constructions involving undative as well as unaccusative verbs, linking, according to Burzio’s generalization, case suspension and lack of an internal argument. The investigation of these constructions and those involving partitive case provides not only a theoretically significant contribution to our understanding of grammar, but also a motivated explanation for a number of empirical problems in French.