Current theories of language acquisition and language-cognition relationships have been largely modeled and tested in neurotypical monolingual English-speaking children. Prior studies have rarely considered the effects of bilingual language contexts, and of input variability in general, on developmental outcomes. In this talk, I will present a series of studies that examine how input variability and individual differences in bilingual experience, language ability and cognition interact to shape learning. The first part of the talk will focus on linking bilingual language input to language and cognitive skills in children with different abilities. I will present data suggesting that children’s cognitive processing capacity may constrain whether exposure to code-switching facilitates or hinders language skills. I will also present data showing that a robust language system may be necessary for dual language exposure to positively influence children’s executive function skills. In the second part of the talk, I will present experimental work that defines variability in a way that is relevant in both bilinguals and monolinguals and investigates the effects of multiple talker and multiple exemplar input on children’s statistical word-learning performance. Results suggest that children can learn and generalize word-referent associations from input that varies in exemplars and speakers, and that bilingualism may bolster learning under conditions of increased input variability. We also found that some forms of variability in the input, but not others, may be especially useful to children with poorer cognitive processing abilities. Together, the findings provide new theoretical insights into how input characteristics and individual differences in language ability interact in children with diverse language histories. Practically, results have the long-term potential to inform treatment and educational strategies targeting language learning in monolingual and bilingual children with language impairment.