In future, an increasing number of people will need to learn continuously in order to orient themselves in the quickly changing world around them. Multimedia communication and multimedia comprehension will be key elements of their learning. Accordingly, it is very important to have a sufficiently deep understanding of the psychological processes behind multimedia comprehension. This understanding should be rooted in theory-driven empirical research about the cognitive processing of multiple representations, particularly of texts and pictures. It should also allow practice-oriented basic recommendations to be derived for the design and usage of multimedia. These recommendations should go beyond everyday knowledge, practical experience, intuition, and the use of seemingly professional surface features. Design of multimedia communication has to be based on sufficiently deep knowledge about the psychological processes involved in comprehension and knowledge construction. Practitioners need to receive scientific support for them to better understand the laws of perception and cognitive processing underlying comprehension and knowledge acquisition.