The effects of methylphenidate and behavioral self-control training on sustained attention were compared in 12 boys aged 6-9 years. Subjects were of low-average intelligence and had academic and behavioral problems including distractibility, short attention span, and impulsiveness. Treatment conditions (baseline, placebo, methylphenidate, and behavioral self-control training) were assigned according to a single-subject randomized blocks design. Attention was measured by the Children's Checking Test (CCT). Methylphenidate improved performance on the CCT and was superior to the other treatment conditions. Several children benefited from behavioral training, but statistical analysis of this change was nonsignificant. These results are consistent with and extend those of previous studies.