A total of 406 heterogeneously grouped students in Grades 3, 4, 6, 7, and 8 in three K through 8 Chicago public schools were assigned randomly to two conditions, ordinary standardized-test instructions (control) and special instructions, to do as well as possible for themselves, their parents, and their teachers (experimental). On average, students given special instructions did significantly better (p < .01) than the control students did on the criterion measure, the mathematics section of the commonly used Iowa Test of Basic Skills. The three schools differed significantly in achievement (p < .05), but girls and boys and grade levels did not differ measurably. The motivational effect was constant across grade levels and boys and girls, but differed significantly (p < .05) across schools. The average effect was moderately large, .303 standard deviations, which implies that the special instructions raise the typical student's scores from the 50th to the 62nd percentile.