How can illustrations motivate learners in multimedia learning? Which features make illustrations interesting? Beside the theoretical relevance of addressing these questions, these issues are practically relevant when instructional designers are to decide which features of illustrations can trigger situational interest irrespective of individual differences. We analysed ratings of illustrations with respect to four potentially interest-triggering features (concreteness, personal relevance, ease of comprehension and unexpected information) and to situational interest. A methodological contribution was to show how multilevel modelling can be applied to take individual differences into account in several respects. Situational interest was predicted by 957 ratings of the four features on an intra-individual level (level 1). Inter-individual differences were controlled by modelling individuals on level 2 (N = 82 high-school students). Concreteness, personal relevance and ease of comprehension of illustrations are what mainly triggered situational interest. Nearly, 55% of the situational interest variance was explained by inter-individual preferences, thus, highlighting the usefulness of multilevel modelling to control for individual differences.