This study investigated the effectiveness of the Assessment and LEarning in Knowledge Spaces (ALEKS) system as a method of strategic intervention in after-school settings to improve the mathematical skills of struggling 6th grade students. Students were randomly assigned to after-school classrooms in which they either worked with ALEKS to improve their math skills or to classrooms where instruction was provided by certified teachers. Students' performance on the Tennessee Comprehensive Assessment Program (TCAP), administered annually to all Tennessee students, indicated that students assigned to the ALEKS condition performed at the same level as those taught by expert teachers (d = 0.09). Also, students participating in our after-school program outperformed non-participating students. (Contains 4 tables and 1 figure.)