Six studies investigated the relationship between production and comprehension by examining how relative clause production mechanisms influence the probabilistic information used by comprehenders to understand these structures. Two production experiments show that accessibility-based mechanisms that are influenced by noun animacy and verb type shape relative clause production. Two corpus studies confirm these production mechanisms in naturally occurring productions. Two comprehension studies found that nouns and verb types occurring in structures that speakers do not produce are difficult to comprehend. Specifically, the probability of producing a passive structure for a verb type in a given animacy configuration, as measured in the production and corpus studies, predicts comprehension difficulty in active structures. Results suggest that the way in which the verb roles are typically mapped onto syntactic arguments in production plays a role in comprehension. Implications for the relationship between production, comprehension and language learning are discussed. (Contains 8 figures and 6 tables.)