The role that illustrations can play in textbooks and other instructional materials is an issue that must appear rather baffling to the instructional materials designer. Focusing primarily on the use of illustrations in textbooks designed for able readers, a literature review has revealed the following: (1) illustrations have been shown in a few instances to facilitate comprehension, although a number of other studies have not been successful in showing this; (2) a number of studies have shown that illustrations can enhance recall, but recall is suspected of often being confounded by comprehension; and (3) that pictures can assist with attitude change in some situations has been demonstrated, while one of their attributes, namely the attractiveness of illustrations, does not seem to have been directly tested. In summary, despite many failures to support the value of illustrations in texts, their value has been confirmed by recent studies and by the long tradition that constitutes the practice of graphic design. Research needs to move on to new frameworks, such as the functional one, where it can help to develop the reasons for illustrations aiding learning and can thus inform future practice. (RL)