Spondylolysis and spondylolisthesis are common causes of low back pain in the competitive athlete. Repetitive loading of the lumbar spine results in stress reactions and spondylytic defects of the pars interarticularis. Spondylolysis and lesser degrees of spondylolisthesis frequently respond to activity restrictions, bracing (in specific situations), and physiotherapy. Spinal fusion is indicated for spondylolysis and spondylolisthesis that remain painful despite nonoperative measures and progressive, high-grade spondylolisthesis. Return-to-play guidelines are made for each athlete individually based on his or her specific diagnosis, response to treatment, and sporting activity.