The purpose of this study was to investigate the effects of various ability grouping and cooperative learning on the academic achievement and motivation. The specific questions set up for this investigation are as follows: First, does various ability grouping have effects on the academic achievement of students? Second, does cooperative learning have effects on The academic achievement of students? Third, does various ability grouping, cooperative learning have effects on the academic achievement of students in the level of learning ability(high, medium, low)? Fourth, does various ability grouping have effects on the academic motivation of students? Fifth, does cooperative learning have effects on the academic motivation of students? Sixth, does various ability grouping, cooperative learning have effects on the academic motivation of students in the level of learning ability(high, medium, low)? This study employed a 2×2×3 treatment by block designs. The between-subjects factors included method of various ability grouping(homogeneous ability grouping in class, heterogeneous ability grouping in class), learning strategy(cooperative learning, small-group learning). The within-subject factor is a learning ability(high, medium, low). The subjects of this study were 144 pupils in the first grade of the middle school in Jeju. Each class (36, 37, 35, and 36) was assigned to one of the treatments: small-group learning with heterogeneous ability grouping, cooperative learning with heterogeneous ability grouping, small-group learning with homogeneous ability grouping, and cooperative learning with homogeneous ability grouping. For a six-weeks period, four groups studied the same content from science studies textbook. The results from this study are as follows : First, there were not significant differences on the academic achievements by the differences of grouping, learning strategies, and level of learning ability. Second, there were not significant differences on the academic motivation by the differences of grouping, but cooperative learning did significantly better than small-group learning in homogeneous ability grouping. Third, on post-academic motivation test scores, small-group learning with heterogeneous ability grouping and homogeneous ability grouping had not effects regardless of different learning ability, but cooperative learning with heterogeneous ability grouping had effects on the medium-learning ability students and cooperative learning with homogeneous ability grouping had effects on the medium- and low-learning ability students.