Recent research on multimedia learning has highlighted the impact of cognitive load on learning outcomes. Cognitive load is induced by the complexity of the material, by the design of the instruction, and by the inferences drawn by the learner when comprehending the presented material. How can cognitive load in multimedia learning be reduced and learning enhanced? The generative theory of multimedia learning outlines the importance of selecting, organizing, and integrating materials in coherent mental representations, operations that are highly affected by attentional processes. Empirical research has shown that learners' attention can be affected by the instruction both in a positive and a negative way. The present paper discusses several instructional design principles to guide learners' attention to relevant aspects of information and information processing. The relationship between cognitive load and attentional processes is outlined as a central topic that has to be investigated in more detail. Finally, implications for the design of multimedia learning materials are discussed.