“Fit checks” refer to the process of mating flight hardware together on the ground before the items are mated on-orbit. The concept seems simple but it can be difficult to perform operations like this on the ground when the flight hardware is designed to be mated on-orbit in a zero-g and/or the vacuum environment of space. Also, some of the items are manufactured years apart so how can the fit checks be performed on these components if one piece is on-orbit before its mating piece is built? Why perform fit checks? How will they help prevent problems that may be encountered by the Astronauts? Should any kind of tools, mockup of flight tools or the actual flight tools be used during the fit check? Do the Astronauts need to perform these fit checks themselves or can anyone perform the fit checks and then provide the results to the Astronauts? This paper will discuss the process of performing Extra-Vehicular Activity (EVA) fit checks and how fit checks should mimic on-orbit operational scenarios. A series of photographs will be included that were taken during fit checks performed on International Space Station (ISS) flight elements in the Space Station Processing Facility (SSPF) at the Kennedy Space Center (KSC) in Florida. Where applicable, the fit check photographs will be followed by on-orbit photographs of the Astronauts performing the tasks during EVA operations. The paper will conclude with lessons learned as a result of these fit checks and how what we have learned so far can be applied to future EVA fit checks as humans move to an operational phase of space exploration.