The purpose of this paper is to consider the concept of "relative age" and to review recent research findings that have demonstrated that relative age is related to a variety of academic and athletic performance measures. The paper is divided into six parts: (1) the relative age concept; (2) relative age and achievement in sports; (3) relative age and achievement in school; (4) relative age or readiness; (5) relative age, hockey, and education; and (6) "neutralizing" the relative age effect in schools. Appended are 14 references. (SI)