A strong relationship between L2 vocabulary knowledge and L2 reading and listening comprehension is well established. However, less research has been conducted to explore correlations between pedagogic interventions to increase vocabulary knowledge and score gains on standardized L2 proficiency tests. This study addresses this gap in the research by analyzing the relationship between extended study of a Test of English for International Communication (TOEIC) word list using spaced repetition software (SRS) and TOEIC score gains. Two classes of Japanese students totaling 60 participants were encouraged to study a TOEIC word list using SRS for 10 months. TOEIC score gains from a pre-test to a post-test were then correlated with the number of flashcard repetitions to investigate the relationship between SRS study and test score gains. Statistically significant relationships (p < 0.05) were found between total SRS repetitions and TOEIC listening and overall score gains. Total word list reviews accounted for 11.4% of the variance in overall TOEIC gains, 6.2% of the variance in reading gain and 7.2% of the variance in listening gains. The authors argue that study of test-specific word lists with SRS may be a useful addition to motivated students' test preparation strategies for standardized foreign language proficiency tests.