The current study investigates a conceptualization of "flexible expertise" as it relates to adult learning within the context of management and leadership training. Three research domains and their relation to metacognitive outcomes are integrated: 1) individual differences in abilities, personality, and mindsets, 2) deliberate practice and routine expertise, and 3) self-regulatory processes. The theoretical focus of the research is on the extent to which metacognitive self-evaluations around person- and management-specific concepts taught during training may act as precursors to flexible expertise. We asked 172 mid-level managers to provide evaluations of concept importance (antecedent), behavioral change (proximal consequence), and impact on job performance (distal consequence) resulting from knowledge acquired during the course of training. A series of hierarchical linear modeling analyses unveil a constellation of core personality characteristics, mindsets, and deliberative processing experiences that together interact to predict metacognitive self-evaluation of impactful training. Our results suggest support for our contention that flexible expertise is a context appropriate, balanced cluster of learning oriented, self-regulatory, and metacognitive processes that moderate and mediate the application of abilities and previously acquired knowledge to problem solution, future knowledge acquisition, and ultimately effective leadership. (Contains 1 figure and 4 tables.)