Advanced knowledge acquisition in a subject area is different in many important ways from introductory learning (and from expertise). In this paper some of the special characteristics of advanced learning of complex conceptual material are discussed. The paper notes that these characteristics are often at odds with the goals and tactics of introductory instruction and with psychological biases in learning. The paper alludes to research in biomedical cognition that has revealed a substantial incidence of misconception attributable to various forms of oversimplification and outlines the factors that contribute to suboptimal learning at the advanced stage. A sketch of a theoretical orientation for more successful advanced knowledge acquisition in ill-structured domains, Cognitive Flexibility Theory, is then presented. This orientation emphasizes: the use of multiple mental and pedagogical representations; the promotion of multiple alternative systems of linkage among knowledge elements; the promotion of schema assembly (as opposed to the retrieval of prepackaged schemas); the centrality of "cases of application" as a vehicle for engendering functional conceptual understanding; and the need for participatory learning, tutorial guidance, and adjunct support for aiding the management of complexity. The paper also discusses a computer hypertext approach that implements Cognitive Flexibility Theory. (Fifteen references are attached.) (Author/RAE)