The present set of studies explore how infants make their first breakthroughs into a second language. I approach this question by experimentally exposing monolingual children to a second language at different points in development in the first two years. The three studies examine how monolingual English-learning infants and toddlers (aged between 8 and 26 months) process and segment speech in an unfamiliar language (i.e., Spanish) and how they learn novel labels in this language. In this regard, I focus primarily on the cognitive and pragmatic mechanisms that might underlie these abilities.

Overall, these studies provide preliminary evidence that monolingual infants are able to process an unfamiliar language at a global as well as at a more refined level, while showing developmental differences in these abilities between 8 and 18 months. Second, this dissertation provides evidence of an emerging understanding of conventionality in a bilingual context in 19-month-old monolingual infants. Specifically, infants' word learning behaviors in a bilingual context suggest that they understand that a new language, or a `communicative context', signals a distinct labeling norm, and this understanding might cue them to accept two labels, one in each language, for a single object. Finally, this dissertation also demonstrates that familiarity with a label in the first language might be a possible mechanism that facilitates learning the equivalent label in the second language.