The aim of the paper is to investigate the role of a commander in military Lessons Learned systems. In order to achieve the aim, the paper presents (1) the architecture of the Lessons Learned capabilities in the U.S. Army, NATO and the Polish Armed Forces, (2) the commander's role in the Lessons Learned process (3) the commander's role in fostering Lessons Learned organisation culture. The paper is based on multiple case study analysis including Lessons Learned systems in NATO, the U.S. Army and the Polish Armed Forces.