An Air Force squadron commander has a tremendous amount of influence over the lives of his/her subordinates. The learning curve of a new commander is steep and time critical. The squadron looks to the commander for leadership and the faster he/she can provide that leadership the more effective their tour will be. The new commander needs every advantage they can get. An understanding of their functions as a commander, the culture of the squadron, and the direction required to meet the expectations of the Air Force, squadron members and their own vision is one of the greatest advantages they can have. The first 90 days of a commander's tour can be used to build a momentum that means the difference between commanding a squadron that is just surviving or commanding a squadron thriving on progress and improvement. This 90 days can pass quickly and should be used to diagnose and assess the squadron's culture, implement immediate and short term changes, and set the squadron on a long term path of growth and progress for the squadron as a whole and each member individually. Diagnostic checklists are provided.