An important component of reading comprehension is the reader's capacity to make inferences that can maintain the coherence between propositions within the text. However, the cognitive and linguistic skills that underlie online inference making remain elusive. The authors aimed to clarify the effects of vocabulary and text comprehension on word-to-text integration during reading. In a self-paced reading study, the authors measured participants' integration of words across sentence boundaries by comparing reading times at a critical word and the subsequent region, when preceded by the same critical word (repetition condition), by a lexically associated word (association condition), or by a word with no direct lexical link (inference condition). Furthermore, the authors assessed vocabulary knowledge, text comprehension, working memory, decoding, and fluid intelligence in the sample. Results showed that richer vocabulary was associated with immediate integration, as evidenced by reading time differences between the critical word and the subsequent word in the inference condition. Other individual differences did not predict self-paced reading times. Findings suggest that lexical knowledge plays a stronger role relative to other individual skills in online inference making and contributes to refining understanding of the mechanisms that underlie efficient reading.