Relative age effects (RAEs; R. H. Barnsley, A. H. Thompson, & P. E. Barnsley, 1985) convey school attainment (dis)advantages depending on whether one is relatively older or younger within annually age-grouped cohorts. In the present study, the authors examined the pervasiveness of RAEs by examining (a) attainment in 4 secondary school subjects, (b) attainment consistency across subjects, (c) pupils enrolled in gifted and talented programs, (d) pupils referred for learning support or identified as having special educational needs, and (e) whether RAEs were related to pupil attendance. For 2004-2005, attainment, program participation, and attendance data for 657 pupils (aged 11-14) at a secondary school in North England were analyzed. Relatively older pupils (i.e., September-November born) attained significantly higher in subjects (except for English), were more likely to attain consistently high scores across subject areas, and be enrolled in gifted and talented programs. In contrast, relatively younger pupils (i.e., January-August born) were overrepresented in learning support referrals and identified as having special educational needs, and were more likely to be among the lowest 20% of attainment and attendees, attending on average school 6 days less. RAEs are pervasive and systematic across the curriculum, implicating maturational and psychological mechanisms. (Contains 3 tables and 3 figures.)