Afro-Caribbean sprinters often reach high performance levels at an early age. Adolescence is a time ofmorphological and physiological changes. This study was designed to analyze the evolution in parameters of shortsprint performance during adolescence in Afro-Caribbean boys, especially the stride number/body height ratio (SN/BH),which is at the interface of technical and morphological factors. Seventy-one 13-year-old boys performed vertical jumpsand short sprint races. The races were filmed with a view to determine stride variables. Anthropometric parameterswere also measured. The same tests were performed two years later. Body height and SN/BH were the main predictorsof sprint performance. The delta of performance was principally explained by stride length and stride number. Althoughdeterioration in technical parameters was expected, the parameters related to body size and stride length were the mainsprint performance predictors rather than explosive force. These results could be useful in developing tests to detectsprint potential in youth.