The authors examined the influence of context meaning consistency on incidental vocabulary acquisition during reading. "Context meaning consistency" refers to informational context that reflected the same meaning (i.e., consistent) or different meanings (i.e., inconsistent) across two self-paced reading sessions for a given item (both sessions on the same day). The first sentence of each sentence-pair item contained informational context, and the second sentence contained a target word (novel target or known control). Acquisition was assessed via surprise memory tests given right after the reading sessions (immediate) and again approximately a week later (delayed). Inconsistent context was generally associated with inflated reading times and less recall than consistent context, and retention was particularly low when the first encounter with the novel target was during the second reading session. Self-paced reading times were also particularly inflated in the second reading session for items in which readers encountered the novel word version of the target for the first time (i.e., known control encountered during the first reading session instead). Acquisition was facilitated most for novel targets that were presented during both reading sessions in consistent meaning context, but suffered the most in the case of consistent context and the novel target initially encountered in the second session. When presented with different meanings for the same novel target across self-paced reading sessions (inconsistent context condition), the intended meaning for the initial presentation was more likely to remain in memory.