Most vocabulary growth during the school-age years occurs incidentally. However, little is understood about the influence of language skills on word knowledge growth during reading. Using a pretest-posttest quasi-experimental design, we examined incidental word learning through reading, considering the presence/absence of supportive context and the role of language ability. Children with a range of language abilities (N = 32), aged 10 years, 6 months to 16 years, 5 months, were exposed three times to rare nouns and verbs within stories or in isolation. Small but significant knowledge gains were found for rare words encountered in context, but not for words in isolation. Language skill predicted overall word knowledge but not rate of word knowledge growth. Findings suggest children with low oral language ability are at a disadvantage in acquiring vocabulary through reading; however, the word learning process may be qualitatively similar for children with varying language skill levels.