Children can acquire novel word meanings by using pragmatic cues. However, previous literature has frequently focused on in-the-moment word-to-meaning mappings, not delayed retention of novel vocabulary. Here, we examine how children use pragmatics as they learn and retain novel words. Thirty-three younger children (mean age: 5.0, range: 4.0-6.0, 21 girls; 85% White) and 33 older children (mean age: 7.5, range: 6.1-9.2, 16 girls, 66% White) participated. During learning, the sound-meaning mapping was either readily available (Direct Mapping condition) or required pragmatic inference (Inference condition). Children's word retention was tested immediately after learning and after 10-15 min of delay. Across both conditions, children performed similarly during learning. There were no significant differences between conditions for either immediate recall or retention in younger children. Importantly, retention (but not immediate recall) in older children demonstrated a significant advantage for the Inference over the Direct Mapping condition. Word retention in the Inference condition was predicted by age and mediated by children's ToM ability. We conclude that children can successfully acquire and retain meanings via pragmatic inference; moreover, the effects of active pragmatic computation on meaning retention grow with development. Such a developmental difference in meaning consolidation is possibly mediated by children's developing ToM skills.