This study investigates the role of L2 age of onset on reading accuracy in a sample of Czech children learning English. The study was performed on two groups of children: a group who had been exposed to English since kindergarten and a group who had been exposed to English since primary school. Forty participants (20 in each group) aged between 8 and 12 years were tested using a standardized reading task. Reading accuracy was calculated with measures of substitutions, mispronunciations, refusals, additions and omissions. The results show that mispronunciations were the most common type of mistake among these children, followed by substitutions, and there was no significant difference between early and late-onset children in overall number of mistakes. However, when considering the subset of substitution errors, early onset children did outperform late onset children. These findings are discussed in relation to previous literature on age of onset effects and reading.