Although Extensive Reading (ER) has been shown to increase reading fluency and comprehension, such benefits are generally slow to appear. The present study investigated the possible contribution of ER to single-semester Test of English for International Communication (TOEIC) reading gains. The participants were 497 first-year students from two annual cohorts at a tertiary institution in Japan. All took a preliminary TOEIC before enrolling in the online ER system "Xreading," which awarded them a word count for successfully completing a short quiz on each book they read for homework. Hierarchical linear regression analyses of end-of-semester ER words read and TOEIC reading scores showed a consistent positive relationship between the two. However, semester increases in the former were not reflected by proportional gains in the latter, a finding possibly explained by greater consistency in ER's implementation across course sections over time. In short, ER words read might in fact be a proxy for general compliance in homework completion rather than a direct cause of TOEIC reading score improvement. [For the complete proceedings, see ED600837.]