The purpose of this study was to investigate the impact of mastery learning on eighth grade language arts students primarily in terms of academic gains, but subsidiary research questions also focused on the impact of mastery learning on student sense of self-efficacy in language arts, student attitudes towards learning language arts, and on student learning styles. This study focused on the grammar portions of language arts; it did not address the reading, writing, and speaking aspects. Results from this quasi-experimental study involved 43 eighth grade language arts students from a rural, relatively homogenous school in the Midwest. Over a four month time period, it was found that mastery learning does seem to have a statistically significant positive impact on student academic success, student sense of self-efficacy, and to some extent, student attitudes towards learning. However, no statistically significant impact was found for mastery learning on learning styles.