What do tautological phrases such as Boys will be boys, A promise is a promise, or War is war mean and how are they understood? These phrases literally appear to be uninformative, yet speakers frequently use such expressions in conversation and listeners have little difficulty comprehending them. Understanding nominal tautologies requires that listeners/readers infer the speaker's attitude toward the noun phrase (e.g., boys) mentioned in the sentence. The purpose of the present studies was to investigate the role of context, syntactic form, and lexical content in the interpretation of nominal tuatologies. Two studies are reported in which subjects rated the acceptability of different tautological constructions either alone (Experiment 1) or with supporting contextual information (Experiment 2). The results of these studies provide evidence that colloquial tautologies can be interpreted differently in different contexts, but that there are important regularities in the syntactic form and lexical content of these phrases which influence how they are understood. Our findings highlight the importance of speakers/listeners' stereotypical understanding of people, activities, and concrete objects in the use and understanding of different tautological expressions. The implications of this research for psycholinguistic theories of conversational inference and indirect language use are discussed.