Blended learning opportunities are expanding for K-12 students in public school settings. As these opportunities increase, researchers and educators seek to discover specific characteristics of the students who are most successful in blended learning environments. The purpose of this study was to investigate the relationship between students' achievement and their attitudes in a self-paced blended mathematics course. A total of 23 high ability eighth grade students participated in the study by completing the Measures of Academic Progress Mathematics Test and the Attitudes Toward Mathematics Inventory to examine the relationship between achievement growth during the course and attitudes at the end of the course. Findings revealed a significant positive correlation between achievement growth and attitudes toward mathematics. Achievement growth was also significantly positively correlated individually with each of the four attitudinal factors studied: value, motivation, enjoyment, and self-confidence. Furthermore, there were significant positive correlations between each of the individual attitudinal factors and overall attitudes toward mathematics. This research demonstrates that high ability students with the most positive attitudes toward mathematics may be more successful in self-paced blended mathematics courses. This is an important step in discovering which students are best suited for this learning environment.