The instructional effectiveness of integrating abstract and realistic visualization was studied using five types of visualization, three levels of general ability and two modes of instruction. The dependent variable was performance on a four-part criterion test representing five different types of instructional objectives, which was administered as both an immediate and a delayed posttest. Subjects were 490 10th grade public school students enrolled in coeducational health classes. Half of the subjects received self-paced written instruction and half received externally paced instruction by an audiotape recording with visuals in booklet form. Instruction included either simple line drawings, realistic color photographs, both line drawings and color photographs, hybrid illustrations of realistic photographs and line drawing segments, or no visuals. Results indicate that the integration of abstract and realistic visualization does not appear to improve effectiveness generally. However, it may enhance externally paced instruction and may reduce achievement differences between students of varied ability, particularly when both types of visualization are presented together. Inclusion of realistic visualization can enhance instruction, while inclusion of abstract visualization should be based on consideration of pacing, general ability, and type of instructional objectives. (LMM)