Previous research suggested that elite youth baseball participants in the Little League World Series exhibited early maturation. The purpose of this study was to compare measures of body size in two samples of youth baseball players with normative data from the United States (NHANES). One sample of youth baseball players was obtained in a mixed cross-sectional design. Players ages 7, 8, 9, and 10 were measured in year one. Participants were measured the second and third year at ages 9, 10, 11, and 12. The total of sample size, including cross-sectional and longitudinal measures, was 243. The second sample of youth baseball players (n=101) were volunteers from 8 of 12 teams participating in the 1997 Dixie Youth World Series. Normative data for the United States (NHANES) was used as comparative data. Measures of height, weight, sitting height, lower limb length, upper limb length, arm girth, calf girth, tricep skinfold, abdomen skinfold were measured on all participants. Two trained anthropometrists conducted all measurements at a location on a university campus. Effect sizes were calculated between the means of height and weight for each sample of baseball players and the normative data. Effect sizes were small and indicated the normative sample was slightly taller and heavier than the Little League volunteers (i.e., ES for height ranged from .14 to .41). Differences were smaller between the Dixie Youth World Series sample and the normative data (ES for height ranged from .12 to .18). Comparisons between measures of body size for groups of player positions (pitchers, first basemen, short stops versus other player positions) were calculated for each sample of youth baseball players. In both samples, pitchers, short stops, and first basemen, as a group, exhibited larger body size (greater height, sitting height, lower limb length, upper limb length) than players at other positions. The mean height, weight, and chronological age of players were calculated for each team in the Dixie World Series sample and were correlated with the number of games won by each team. Height (r=.76) and chronological age (r=.87) significantly predicted the number of games won by each team during the series. In the Dixie Youth World Series, the teams who were taller and chronologically older than the other teams were more successful and won more games. Collectively, the results suggest that larger body size is an advantage in terms of team success and assignment to skilled positions. Keyword(s): athletics/sports, performance, youth sports