This paper examines three candidate explanations for why American forces learned faster than did their British counterparts during the Second World War: (1) American leaders were better mentally and intellectually prepared to understand and react to the lessons of modern war than were the British; (2) there were stronger bureaucratic forces acting to inhibit innovation and learning in the British than the US Army; and (3) the mechanisms in the British Army by which lessons could be codified and transmitted throughout the force were, relative to those found in the US Army, underdeveloped.