Spatial reasoning is the capacity to manipulate visual representations. Performance on spatial reasoning tasks has been related to testosterone, which increases in males during pubertal development. Nevertheless, it is not clear if children of different pubertal development have indeed differences in pubertal development, since the studies have not controlled the age and education of participants.Participants were 36 girls and 28 boys (10.28±0.98 years; 5.13±1.0 completed school years). The score on the Pubertal Development Scale was used to create high and low pubertal development groups, which had no differences on age or education. To assess spatial reasoning the Spatial Abilities Task was employed, in which an irregular figure is presented along four other figures, the participant has to select the figure that forms a square when joined with the first . Number of correct responses and time to respond were considered as indices of spatial reasoning. Boys with higher pubertal development (11.71±2.64 responses) had more correct responses (U=32.50, p<0.01) than those of lower pubertal development (9.14±2.24 responses) but had no differences on response time. Girls had no differences on correct responses but those with higher pubertal development (2.03±0.7 min) took less time to respond (U=99.00, p<0.05) than those of lower pubertal development (2.58±1.0 min). Pubertal development improves spatial reasoning in boys and in girls, independently of age or education. This implies that children of the same age and grade have a different capacity to manipulate visual representations, which are crucial for academic and sport activities.