Three experiments investigated the conditions under which pictures facilitate learning. In Experiment 1, confusing verbal relationships were supplemented with pictures that illustrated the key concepts in each verbal relationship (base pictures), illustrated the key concepts in more elaborate arbitrary relationships (pictures of arbitrary elaborations), or illustrated the key concepts in ways that helped clarify the verbal relationships (pictures of explanatory elaborations). All three types of pictures facilitated the retention of the verbal relationships, although pictures of explanatory elaborations were superior to other types of visual illustrations. In Experiment 2, the facilitative effects of base pictures depended on a schematically unique illustration of the key concepts in a single image. In Experiment 3, picture facilitation effects were constrained by the type of verbal elaborations that accompanied the pictures. Specifically, base pictures and pictures of arbitrary elaborations did not facilitate the retention of confusing verbal relationships that were elaborated with explanatory information, and actually interfered with the retention of those explanatory elaborations. The implications of these results are discussed.One strategy frequently used to help people understand new and confusing information is to represent that information in a visual illustration. Pictures or graphic illustrations are commonly used in lectures, ftlms, textbooks, instruction manuals, computer software, and scientific articles to help people understand and learn new information. Despite the extensive use of visual illustrations, it remains unclear why pictures facilitate the comprehension and retention of verbal information and what factors influence the effectiveness of pictorial illustrations (e.g., Bluth, 1981;Brody, 1981;Levin, 1981;Samuels, 1970).One way pictures could facilitate the comprehension and retention of information is by helping people relate new information to previous experience (elaboration). Substantial research suggests that comprehension and/or retention can be enhanced by providing additional elaborations during study