In an effort to develop screening criteria to allow nonphysicians to detect physically immature boys prior to interscholastic sports competition, 364 male adolescents were studied as part of their group preparticipation health evaluation. Handgrip and self-assessed Tanner stage were measured, in addition to the routine preparticipation health evaluation procedures. Of the 118 boys who were Tanner 3 or less (immature), 103 (87%) had weak grips (less than 55 lb [24.9 kg]), and 88 (75%) rated themselves as Tanner 3 or less. Of the 246 boys who were greater than Tanner 3 (mature), 223 (91%) had strong grips (greater than or equal to 55 [24.9 kg]), and 229 (93%) rated themselves as greater than Tanner 3. Six of the 118 immature boys (5%) had both a strong grip and mature self-assessed Tanner stage; three of the 246 mature boys (1%) had both a weak grip and an immature self-assessed Tanner stage. Only 67 of 364 (18%) boys had grips and self-assessed Tanner staging that were discordant. Use of grip strength and self-assessed Tanner staging may obviate the need for physician assessment of Tanner stage for the majority of adolescent boys prior to participation in collision sports.