Over the past 25 to 30 years, the active Air Force has made dramatic changes in the organization and structure of fighter aircraft maintenance units, while Air National Guard (ANG) maintenance units have remained substantially the same. The acceptance of the gaining-command concept in 1960 effectively bound the ANG to abide by the training and policy guidelines of the active Air Force. According to this concept each Air National Guard unit is aligned by mission with an active Air Force major command. During peacetime each major command is responsible for providing policy guidelines and monitoring the training of each of its designated units to include conducting operational readiness inspections (ORI). Upon mobilization the various Guard units are integrated with their gaining command to complete a total force structure capable of meeting wartime contingencies. The Vietnam experience taught us some lessons about organizing for combat and training the way we plan to fight. The active tactical air forces (TAF) responded to those lessons learned and to a changing environment by changing the structure of their maintenance organization. The changes that were made could affect the ANG's ability to integrate with the active forces when mobilized and to interact with them during peacetime training, exercises, and deployments. This study analyses and assesses the changes in organization and structure of the active Air Force and ANG fighter maintenance units from the time the ANG became a separate reserve component in 1946 to the present-day organization, paralleling it with the active Air Force. It takes the reader from the ANG maintenance unit's beginning, through the changes that occurred over the years and the reason for the changes, to the present-day organization. It then provides a glimpse at the future maintenance organization.