Tasks of speeded naming, phonological awareness, word identification, nonsense word repetition, and vocabulary, along with two measures of morphological awareness (morphological structure awareness and morpheme identification), were administered to 115 kindergartners and 105 second graders. In the combined sample, 48% of the variance in vocabulary knowledge was predicted by the phonological processing and reading variables. Morphological structure awareness and morpheme identification together predicted an additional unique 10% of variance in vocabulary knowledge, for a total of 58% of the variance explained; both measures of morphological awareness were uniquely associated with vocabulary knowledge. Results underscore the potential importance of different facets of morphological awareness, as distinct from phonological processing skills, for understanding variability in early vocabulary acquisition.