The purpose of this study was to compare the academic achievement of students who were grouped for reading instruction and those not grouped for reading instruction. Participants were 132 second-grade and 138 fifth-grade students at 16 elementary schools in USD 259. Students' academic achievement was measured using the district benchmark reading assessment; wh1le the type of grouping used for reading instruction was determined through the use of a questionnaire completed by building principals. Findings from this indicated that a student's race/ethnicity, gender, or socioeconomic status had less to do with their academic achievement than the way in which they were instructed for reading. Only a few of the findings of this study are consistent with previous research, indicating a need for further research in the area of ability grouping.