The purpose of this study was to investigate children’s synchronization abilities with various external stimuli in relation to their music aptitude levels. Forty-four children between five and seven years of age took part in this study. I examined children’s synchronization accuracy through tapping tasks with four stimuli: isochronous, familiar melodic, unfamiliar melodic, & rhythmic. Children were assigned to either duple or triple meter conditions. The order of melodic and rhythmic sequences was counterbalanced and randomly assigned. Gordon’s Primary Measures of Music Audiation was used to determine children’s tonal and rhythm aptitude levels. A mixed ANOVA with data from 36 children revealed a three-way interaction (rhythm aptitude × meter × stimuli) in synchronization accuracy. For students with low rhythm aptitude in the triple meter group, their mean of synchronization error was higher in the rhythmic condition than all other conditions. When tapping with triple meter rhythmic sequence, children with high rhythm aptitude synchronized better than students with lower rhythm aptitude. For students with lower rhythm aptitude, students in the duple meter group synchronized better with the rhythmic stimulus than the triple meter group. The role of structural features of stimuli, familiarity, and music aptitude in young children’s synchronization accuracy was discussed.