A study tested the hypothesis that the production of derivational (as contrasted with grammatical) morphemes is acquired through a systematic development of three distinct psychological processes: comprehension, segmentation, and production, regardless of whether the individual is a first- or second-language learner. The subjects were 32 children, grades 2-5, who were non-English-speaking Spanish speakers, limited-English-speaking Spanish speakers, Spanish-English bilingual, and monolingual English speakers. The test used consisted of 24 items probing the existence in the child of a generalized rule for deriving morphemes. Results suggest that the hypothesized processes are not systematically consistent across related forms of English, but vary within the morpheme type examined. Monolinguals showed the same facility across morpheme types, limited-English-speakers were more proficient in suffixes than prefixes, and bilinguals showed the reverse pattern. In native Spanish, a progression of processes emerged, with segmentation the easiest and first learned. Suffixes were better known than prefixes in Spanish. (MSE)