Word and nonword vocalizations produced by two groups of children aged 8-28 months were studied. The first group included six children whose speech was recorded monthly for 12 months. The second group contained 21 children. In both, only spontaneous vocalizations were recorded. Each sample was examined for frequency of word and nonword forms. A word was defined as a phonetic form recognizable to both caregiver and researcher and used consistently and meaningfully. A nonword production was any phonetically transcribable vocalization not considered a word. Reflexive vocalizations (e.g., sneezes) were not used. Nonwords accounted for over 50% of vocalization before 19 months, with a gradual decrease to 20% by 25 months. All children were still producing nonword vocalizations at the end of the study, suggesting that nonwords contribute to vocalization of children actively acquiring language. It is suggested that some nonwords identified in later periods of the study also functioned pragmatically as words. In addition, frequency of usage and difficulty in distinguishing between words and nonwords open to question the relevance of the distinction. It is concluded that both word and nonword forms should be given special consideration in the assessment of a child's articulatory capabilities. A 22-item bibliography is included. (MSE)