This book reports on research exploring the influence of illustration design features on learners'' comprehension of associated text. The research examined the extent to which variations in the design of illustrations could clarify ambiguous incomplete text passages and so direct learners to an appropriate choice of prepositions missing from those passages. Appropriate choice was assumed to result from the construction of a suitable mental model of the referent situation portrayed by the text and picture combination. The focus of the research was upon Indonesian students learning English. This cumulative investigation began by characterising current usage of pictures in the teaching of English prepositions, identifying prepositions students found difficult, and determining possible sources of these difficulties with respect to the design of pictures (both static and animated) used to support the associated text. The research indicates that the mere provision of accompanying pictures is insufficient to ensure they support effective comprehension of text. Rather, the particularities of design of both static and animated pictures are central to their educational effectiveness.