Lexical acquisition ability for aurally taught words was studied in fourthgrade children. Reading ability, intelligence, and working memory were evaluated as predictor factors in vocabulary learning. Reading ability was found to predict facility at learning the novel phonological sequences, while intelligence was the only factor which accounted for performance level for the semantic content of the words. The working memory measure, digit span, failed to make a significant contribution to either the phonological or semantic outcome measures. Examination of two subgroups of skilled and less-skilled readers indicated that less-skilled readers had more difficulty acquiring the phonological information for new words. No between-group differences were found in long-term retention or in the ability to provide definitions for the newly learned words. The findings suggest that the vocabulary deficits of less-skilled readers stem, at least in part, from difficulty establishing accurate phonological representations for new words.