Learning even just one language is a complex process. But young children have the potential to learn more than one language. Again, what is most important is that you talk with your child in the language with which you are most comfortable, so you can have the types of conversations that promote your child's thinking and language development.
It is also important to be a good language model and not mix up languages. That is, when talking with your child in English, don't mix in phrases and sentences from your native language. However, don't be surprised if your child uses words from both languages in one sentence. This is not a sign of confusion, but her current way of communicating what she wants to say.
Excerpt from "Learning Two Languages." Reprinted with permission from PBS Parents.