The role of implicit learning in incidental vocabulary acquisition while reading narrative texts was examined in 3^rd-5 ^th grade students. This study was conducted to experimentally test whether implicit learning contributed to vocabulary acquisition. The literature for both implicit learning and incidental vocabulary acquisition are expansive. However, there exists little literature, either theoretical or empirical, that directly explores the connection between implicit learning and incidental learning. There is even less literature that explores the connection in the context of vocabulary acquisition. In the past decade and a half, two theoretical frameworks have emerged that can be used to examine this connection. This study provided empirical evidence for such a connection between implicit learning and incidental vocabulary acquisition by measuring the unique contributions of several factors (reading comprehension ability, decoding ability, fluency, word identification ability, working memory, and implicit learning ability) to incidental vocabulary acquisition. Results indicate that implicit learning ability does contribute to incidental learning of a word's form, but does not contribute to the incidental learning of a word's meaning. Results of this study also indicate that implicit learning is domain-specific in that learning from one domain is unrelated to learning in another domain. The results of this study may prove useful to educational researchers and educators as they develop interventions to facilitate vocabulary growth in students by identifying those students who struggle with incidental vocabulary acquisition.