When we learn new and complex materials, our cognitive processing capabilities are usually severely reduced due to limited working memory capacity. Learner expertise in a specific domain decreases those limitations by enabling the use of the experts organised knowledge base. In many instructional situations, however, expertise may also trigger additional cognitive load because of the processing of redundant information. Recently, strong evidence has emerged that instructional techniques, which are highly effective with novice learners, can lose their effectiveness and even have negative consequences when used with advanced learners. As learners become more knowledgeable in a domain, instructional techniques and procedures often need to change radically in order to remain efficient. To tailor instruction to levels of learner knowledge in computer-based learning environments, it is critical to have a simple and rapid measure of learner expertise suitable for real-time testing. The primary goal of this book is to provide the theoretical background and research-based recommendations on instructional techniques and diagnostic assessment methods that are suitable for advanced learners in multimedia learning environments.