Abstract: This article investigates the effects of the maintenance of Japanese as a heritage language on English and overall academic achievement. The interrelationships amongjapanese oral and writing proficiency, SAT I Verbal, SAT I, and high school grade point average (GPA) were examined. The participants were 31 second generation Japanese-American college students in Southern California, and the data was obtained from the subjects' self reports. No significant relationships were found between Japanese proficiency and English proficiency or between Japanese proficiency and overall academic achievement. The study suggests that the maintenance of a heritage language does not produce any negative effects on English development and on academic achievement.