The relationship between idiom familiarity and idiom comprehension was investigated. Familiar and less familiar idioms were presented in three types of sentences. The sentences were biased toward the idiom's literal meaning, biased toward the idiom's idiomatic meaning, or unbiased toward either meaning. Reading times for sentences containing less familiar idioms were longer than for sentences containing familiar idioms, but there was no significant main effect for sentence type. The familiarity by sentence type interaction was significant. In literal sentences, less familiar idioms required more reading time than familiar idioms. In idiomatic sentences, less familiar idioms required more reading time than familiar idioms. The results are interpreted as being consistent with the idiomatic processing model, which proposes that processing of an idiom's idiomatic meaning precedes processing of its literal meaning.