The aim of this research was to operationalize and validate a lessons-learned sharing process for supporting organizational learning. I validated the process by measuring and evaluating the effects of the process on decision-making (i.e., management) performance. The research results provide tangible evidence about the effects of a lessons-learned sharing process to support organizational learning. A lessons-learned sharing process does improve decision-making performance as measured by decision quality. A three phase research process was used. The first phase consisted of a task analysis at an industrial site. The results of the task analysis served as the basis for an experiment. The second phase was a laboratory experiment. Sixty students participated in the experiment. The experiment involved twenty groups of three subjects. One subject completed a task and constructed a lesson learned based on feedback from his or her decisions. The next two subjects used different parts of the lesson learned to solve the same problem. The factors studied in the experiment were the content (no lesson learned, a lesson learned containing only recommendations, and a lesson learned containing the original set of decisions, results, and recommendations) and structure (informal or formal). Both quantitative and qualitative data were collected. The quantitative results of the experiment show: 1) having a lesson learned was better than not having a lesson learned; 2) a formal or structured lesson learned had a greater effect on decision quality than an informal or unstructured lesson learned; and 3) the formal or structured lesson learned produced an higher-quality lesson learned. The qualitative results show: 1) subjects want explanations for the recommendations in the lesson learned; 2) the accuracy and consistency of a lesson-learned content needs to be ensured because people may use the lesson learned as an answer without further work; and 3) prompts for eliciting the information in a lesson learned need to be developed. Subjects used the lesson learned in six different ways when solving the problem. The problem consisted of making a set of decisions for a manufacturing shift. The third phase of the research involved a follow-up at the original industrial site. The purpose of this second field study was to gain an insight into how the experimental findings related to a field setting. Implications are discussed for the theory of organizational learning and users of lessons-learned sharing processes in organizations. / Ph. D.