Experimental research has shown that English-learning children as young as 19 months, as well as children learning other languages (e.g., Mandarin), infer some aspects of verb meanings by mapping the nominal elements in the utterance onto participants in the event expressed by the verb. The present study assessed this structure or analogical mapping mechanism (SAMM) on naturalistic speech in the linguistic environment of 20 Spanish-learning infants from Argentina (average age 19 months). This study showed that the SAMM performs poorly – at chance level – especially when only noun phrases (NPs) included in experimental studies of the SAMM were parsed. If agreement morphology is considered, the performance is slightly above chance but still very poor. In addition, it was found that the SAMM performs better on intransitive and transitive verbs, compared to ditransitives. Agreement morphology has a beneficial effect only on transitive and ditransitive verbs. On the whole, concerns are raised about the role of the SAMM in infants’ interpretation of verb meaning in natural exchanges.