This study explored whether a daytime nap aids children's acquisition of letter-sound knowledge, which is a fundamental component for learning to read. Thirty-two preschool children in Sydney, Australia (M[subscript age] = 4 years;3 months) were taught letter-sound mappings in two sessions: one followed by a nap and the other by a wakeful period. Learning was assessed by explicit letter-sound mappings ("Which sound does this letter make?") and knowledge generalization tasks ("Here's "Tav" and "Cav," which one is /kav/?"). Results from the knowledge generalization task showed better performance after a nap than after wake. However, no nap benefit was found for explicit letter-sound knowledge. This study provides initial evidence that naps could be beneficial for preschool children's learning of letter-sound mappings.