A sign decision task, in which deaf signers made a decision about the number of hands required to form a particular sign of American Sign Language (ASL), revealed significant facilitation by repetition among signs that share a base morpheme. A lexical decision task on English words revealed facilitation by repetition among words that share a base morpheme in both English and ASL, but not among those that share a base morpheme in ASL only. This outcome occurred for both deaf and hearing subjects. The results are interpreted as evidence that the morphological principles of lexical organization observed in ASL do not extend to the organization of English for skilled deaf readers. © 1989 Psychonomic Society, Inc.