This chapter examines expertise in complex and ill-structured domains from the perspective of cognitive flexibility theory (CFT). The emphasis is on adaptation under conditions of “ordinary novelty.” An approach to situational novelty via meta-features of an adaptive mindset that generalizes across cases in ways that content does not, and that fosters the skill of novel rearrangement of previously encountered case features in ways that are adaptive to new situations, is presented. The chapter describes CFT’s theoretical and empirical approach to combating rigidity and oversimplification, and to accelerating expertise in assembling “schemas of the moment” with learning based on the principled development and application of computer-supported case-based environments. Receiving special emphasis are many new modes of deliberate practice of adaptive flexibility. The chapter concludes with societal implications for today’s rapidly changing and increasingly complex world.