This study was concerned with the effect of subsuming concepts on student achievement and the interaction effect of subsumers with high and low organizing ability. One hundred forty-three subjects (Ss), enrolled in six sections of a class in undergraduate chemistry, were administered an organizing ability test and rank ordered according to the results. The median break technique was used to form two groups--good organizers (GO) and poor organizers (PO). Ss within each of these groups were then randomly assigned to three treatments. Treatment 1 Ss received a 500-word advance organizer followed by a 2,500-word learning passage. Treatment 2 Ss received the same organizer preceded by the learning passage. Treatment 3 Ss received a historical nonorganizer and the learning passage. A 3 x 2 ANOVA design was employed to analyze the results of a test over the learning passage. There were no significant differences among treatments, but GO Ss achieved significantly higher scores than did PO Ss. (Author/BR)