Instruction on problem solving in particular domains typically relies on explanations from experts about their strategies. However, research indicates that such self-reports often are incomplete or inaccurate (e.g., Chao & Salvendy, 1994; Cooke & Breedin, 1994). This article evaluates research on experts' cognition, the accuracy of experts' self-reports, and the efficacy of instruction based on experts' self-reports. Analysis of this evidence indicates that experts' free recall of strategies introduces errors and omissions into instructional materials that hinder student success. In contrast, when experts engage in structured knowledge elicitation techniques (e.g., cognitive task analysis), the resultant instruction is more effective. Based on these findings, the article provides a theoretical explanation of experts' self-report errors and discusses implications for the continued improvement of instructional design processes.