Purpose: This experiment examined English- or Spanish-learning preverbal (8-9 months, n = 32) and postverbal (12-14 months, n = 40) infants' learning of word-action pairings prior to and after the transition to verb comprehension and its relation to naturally learned vocabulary. Method: Infants of both verbal levels were first habituated to 2 dynamic video displays of novel word-action pairings, the words /wem/ or /baef/, spoken synchronously with an adult shaking or looming an object, and tested with interchanged (switched) versus same word-action pairings. Mothers of the postverbal infants were asked to report on their infants' vocabulary on the MacArthur-Bates Communicative Development Inventories (Fenson et al., 1994). Results: The preverbal infants looked longer to the switched relative to same pairings, suggesting word-action mapping, but not the postverbal infants. Mothers of the postverbal infants reported a noun bias on the MacArthur-Bates Communicative Development Inventories; infants learned more nouns than verbs in the natural environment. Further analyses revealed marginal word-action mapping in postverbal infants who learned fewer nouns and only comprehended verbs (post-verb comprehension), but not in those who learned more nouns and also produced verbs (post-verb production). Conclusions: These findings on verb learning from inside and outside the laboratory suggest a developmental shift from domain-general to language-specific mechanisms. Long before they talk, infants learning a noun-dominant language learn synchronous word-action relations. As a postverbal language-specific noun bias develops, this learning temporarily diminishes.