A review of the literature on the function of pictures in prose learning indicates that visual illustrations are helpful to children's learning, but that visual imagery has inconsistent effects on prose learning, although it seems to have potential for assisting those with adequate word recognition but low comprehension. A conceptual framework has been hypothesized in order to reevaluate existing research and to permit a formal distinction among the several functions that prose-learning pictures likely serve. The functions hypothesized are decoration, remuneration, motivation, reiteration, representation, organization, interpretation, and transformation. Two of these functions, the representation function and the transformation function, have proved useful in differentiating between the magnitude and consistency of picture effects that can be anticipated from one prose-learning study to the next. The framework can prove helpful in identifying the kinds of variables that need to be controlled for when looking for pictures in prose effects, as well as the kind of research that still needs to be conducted to isolate the contributions of specific picture components. (MKM)