A 30-year contribution of the Space Shuttle Program is the evolution of NASA's social actions through organizational learning. This study investigated how NASA learned over time following two catastrophic accidents. Schwandt's (1997) organizational Learning System Model (OLSM) characterized the learning in this High Reliability Organization (HRO). The research synthesized findings from NASA's investigations following the failure of the Shuttles Challenger and Columbia accidents with findings gained through interviews with experts, management, and executives who played a role in NASA during both flights. The data revealed seven themes that demonstrated both organizational learning and learning opportunities that were missed. Analysis of the data resulted in three conclusions from this research. First, NASA has learned that it has an oscillating equilibrium point between exploration and exploitation. Second, NASA's learning after each accident was limited by its presence in the public stage. Finally, NASA recognized that the evolved roles and routines in the organization were not sufficient to transfer lessons learned through time. The conclusion from this research re-emphasized the need for a systematic way to provide awareness of an organization's risk posture in the exploration versus exploitation continuum. This research also contributed to theory and methodologies of the OLSM. The conclusions from this research could provide insight to other HROs. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]