Purpose: Adults recognize words that are acquired during childhood more quickly than words acquired during adulthood. This is known as the Age of Acquisition (AoA) effect. The AoA effect, according to the integrated account, manifests in tasks necessitating greater semantic processing and in tasks with arbitrary input-output mapping. Compound words allow us to investigate this account due to the arbitrary input-output mapping between the compound word itself and its morphemes, which requires greater semantic processing. Method: Forty-eight British English students in each experiment completed an unspaced (Experiment 1; n = 48; 83% female; M[subscript age] = 19.73), spaced (Experiment 2; n = 48; 83% female; M[subscript age] = 19.04), auditory (Experiment 3; n = 48; 63% female; M[subscript age] = 19.83), and cross-modal (Experiment 4; n = 48; 52% female; M[subscript age] = 19.81) lexical decision task (LDT) using a regression design on 226 compound words. Results: We observed that the AoA of the compound word affected accuracy across all tasks, whereas the AoA of the compound word influenced recognition latencies across all tasks except cross-modal LDT. Discussion: The results suggest that the influence of the AoA effect and of semantic predictors is largest in unspaced compound words and smallest in cross-modal LDT. This indicates that the AoA effect in word recognition is in line with the integrated account.