The combined contributions of word age of acquisition (AoA) and word frequency (rated and objective) to word retrieval speed and accuracy were investigated, using a picture-naming paradigm. Results from two fully factorial studies revealed that both AoA and word frequency reliably facilitate the speed and accuracy of word retrieval. Furthermore, word frequency and AoA interacted across delay (0, 750, 1,500, and 2,250 msec) in Experiment 2. This resulted in word frequency's playing a stronger role for late-acquired words across delays. It is concluded that both AoA and word frequency play a fundamental role in lexical retrieval. The results are also consistent with the view that both factors affect the same processing stages.