This book presents a theory which proposes a modular relationship between aspectual role information, and conceptual or thematic representations of lexical semantic information. Language-specific generalizations about linking are argued to be expressed in thematic or conceptual representations, while universal linking generalizations are expressed in aspectual representations. Consequently, this theory has implications for language acquisition. A number of recent works have treated aspect or lexical semantics or argument structure in their own right, but none have focused on aspect as central in the relation between lexical semantics and syntactic argument structure.