The aim of this study was to investigate the construct validity of the “High/Scope Beat Competence Analysis Test” (High/Scope Educational Research Foundation, 2005), examining a) the effect of both age and sex on the children’s H/SBCAT scores and b) the internal consistency of the battery test. Four hundred and fifty eight preschool and primary school children from Greece (238 boys, 220 girls), 5-8 years old (M =6.45 years, SD =1.12) participated in this study. For the data analysis both an ANOVA and a MANOVA were applied with the total battery score and the eight item scores being the dependent variables, respectively. Sex (F1,450=27.371, p< .001, η2= .057) and age (F3,450=21.804, p< .001, η2= .127) were found to have a significant effect on children's total battery scores but moderate η2 coefficient. Studying the eight tests individually, girls had better performance than boys with η2< .14, and each age group performed better than the younger groups in all the tests (η2< .14) except "toe-tapping pad with alternating feet" in both tempos (120 and 132 beats/min). The internal consistency of the "H/SBCAT" was supported. The aforementioned results raise concerns about the validity of the "H/SBCAT". A modification of the battery items is suggested, in order "H/SBCAT" validity to be improved.