The external provision of examples has proven the most successful approach to aid learning and application of declarative concepts (i.e., abstract concepts denoted by key terms and short definitions that can be applied to a wide variety of scenarios). The current experiment sought to further this line of research by exploring the effect of using thematically varied examples on learners' ability to classify novel exemplars and near misses of five system principles that cut across thematic domains. Results revealed that thematic variation increased learners’ ability to reject near-misses and, more crucially, to classify novel exemplars from domains not covered by the studied examples. The fact that this enhanced flexibility was unaccompanied by poorer performance in rejecting near misses or classifying new items from domains covered by the learned examples renders this strategy readily applicable in instructional settings. We end by discussing possible mechanisms that could potentially explain the observed advantage of thematically varied examples