Although computer games as a way to improve students' learning have received attention by many educational researchers, no consensus has been reached on the effects of computer games on student achievement. Moreover, there is lack of empirical research on differential effects of computer games on diverse learners. In response, this study empirically examined the effects of playing computer games on math achievement of 4th graders, with special focus on gender and language minority groups. The study used the 2005 National Assessment of Educational Progress (NAEP), a nationally representative database of the USA. The study performed regression analyses using more than 170,000 U.S. 4th-grade students by applying a proper weight and considering design effects to have high generalizability. The study specified three models for analyses: ELL Model, Gender Model, and Interaction Model. The results showed that English-speaking students who played computer math games in school every day displayed significantly lower math achievement than those who never played. Contrastingly, positive effects of daily computer use were noted among male students whose first language was other than English. Male language minority students who daily played computer games in math demonstrated higher math performance scores compared with their male English-speaking counterparts who never played. (Contains 2 tables and 2 figures.)