Generals Lewis Walt, Raymond Davis, and Lieutenant General Victor Krulak had highly successful Marine Corps careers beginning with their commissioning in the 1930s. The purpose of this monograph is to examine their development as young officers from pre-commissioning until they assumed battalion command and to identify common trends potentially applicable to the Marine Corps officer procurement and development system today. The methodology for this study included a review of the officers' Official Marine Corps personal records, interviews, and a document search at the United States Marine Corps' Archives, History Division and the Marine Corps Heritage Foundation. The research examines the pre-commissioning education, activities and experiences of each officer prior to joining the Marine Corps, their wide and varied experiences as young officers in the operational forces, and the impact of mentorship on the officers' early careers. The officers commissioned in the 1930s benefited from several characteristics that are different from today's newly commissioned officers. First, they had a wide range of experiences prior to commissioning, including military experience in the Reserve Officer Training Corps or the National Guard. Second, their first tours in the operating forces provided them with a multitude of opportunities to lead Marines both in the United States and abroad. Finally, due to the small size of the officer corps, and the nature of the service, a very active, yet informal mentoring network not only guided the young officers, but also provided them opportunities. This monograph contains three specific recommendations for the Marine Corps in the development of junior officers. First, the Marine Corps needs to improve the formal aspects of developing junior officers through a refocus and re-emphasis of the Supplemental MOS program and an implementation of a pathway for young officers to observe units in action prior to them assuming their first operational billet. Second, formalize and incorporate a program to expose young officers to the responsibilities and duties from marines who are veterans of the current environment. Third, increase the senior officers' and staff non-commissioned officers' education and awareness of the importance of mentoring to the development of junior officers and encourage the development of meaningful mentoring relationships between the junior and senior officers.