Spondylolysis in athletes represents a spectrum of injuries to the pars interarticularis due to overuse. These injuries are becoming more prevalent with year-round sports participation for skeletally immature athletes. The mechanism entails abnormal trauma to normal bone with repetitive lumbar extension. The injury begins as a unilateral stress response or bone bruise seen on MRI and then can progress to unicortical fracture, followed by bicortical fracture. Continued stress can ultimately lead to spondylolisthesis, which can have lifelong implications. This chapter reviews the current literature and expert opinion regarding the demographics, presentation, evaluation, and management of these injuries in athletes.