This study explores the relationship between small, differentiated reading groups and fourth-grade students' reading motivation. Using self-study methodology, the author examined her own process of implementing these reading groups through two cycles of action research. Data were analyzed from two different administrations of the Motivations for Reading Questionnaire, as well as from the author's narrative journal entries, written student reflections, small-group and individual interviews, and a critical friend's observations. Findings indicated that small, differentiated reading groups that emphasized social interaction and student choice led to a class culture of reading and promoted students' reading motivation. Students linked their learning in these groups to their written assignments and tended to devalue the group discussions. In addition, implementing the reading groups minimized the author's own performance gap and contributed to greater satisfaction in her own practice. These findings have implications for the design and implementation of differentiated reading groups, as well as for those who support novice teachers.