A random sample of primary-grade teachers from across the United States was surveyed about within-class ability grouping in reading. Sixty-three percent of participants reported using within-class ability groups. Groups are smaller and more flexible than those formed in the past, with teachers emphasizing teaching comprehension, reading vocabulary, and other basic reading skills to each of their groups. Most teachers reported that they used within-class ability grouping because it helps them meet their students' instructional needs, although there were some reasons for concern. For instance, students in lower ability groups spend more time involved in noninstructional activities, are less likely to be asked critical comprehension questions, and are given fewer opportunities to select their own reading material.