This paper argues that pedagogic efficacy of multimedia packages (interactive multimedia presentations) cannot be achieved by experimental research in the absence of a detailed pedagogical screenwriting framework. Following a summary of relevant literature, such a framework is offered, consisting of micro-level design guidelines. The guidelines are grounded in the author's experience of producing multimedia packages at the UK Open University. They concentrate on achieving synergy between images, narration and key-word text. Their utility for practitioners is contrasted against typically rudimentary "design principles" whose support is derived from experimental research of low ecological validity. Nevertheless, future research to further refine the guidelines is recommended so as to develop them into practicable design principles. Some of the guidelines promise an improvement in addressing cognitive load beyond that offered by Cognitive Load Theory.