The effect of school entry age on children’s later performance is a long-debated topic without any convergence. Besides, existing studies have mostly limited themselves to examining the impact of entry age on children’s cognitive achievements. In Germany, where different entry-age regulations exist across federal states and academic tracking takes place very early, it is crucial to investigate whether these differential school entry ages affect children’s outcomes. This study, based on the longitudinal data available from the National Educational Panel Study, investigates the possible entry-age effect on children’s willingness to make an effort and their school enjoyment in the German elementary school context. The study found a positive entry-age effect only for willingness to make an effort but not for school enjoyment, and the existing entry-age effect decreases over time. Therefore, empirical evidence confirms that, in Germany, the entry-age effect persists in the short run and some child outcomes seem more sensitive to entry age than others. These are important findings in the German context where students’ academic tracking starts from lower secondary schooling and entry-age effects may significantly influence it.