A slide rail assembly adapted to mount an object to a rack includes first through third rails. The first rail is mounted to the rack. The second rail is movably connected to the first rail and includes a reinforcement structure having a first portion and a second portion opposite the first portion. The third rail is movably connected to the second rail. When the slide rail assembly is in a fully pulled out position, each of the second and third rails is at an extended position with respect to the first rail, the second rail is located between the first and third rails, and the first and second portions of the reinforcement structure correspond in position to the third and first rails respectively.