This article provides an overview of the psycholinguistic research concerning the processes and representations that bilinguals use while processing language. We review the lexical, semantic, and syntactic levels of bilingual processing. The main conclusion from this review is that the different languages of bilinguals strongly influence each other during processing. Therefore, we end with a brief overview of some recent research about how bilinguals are able to keep this interference under control. Throughout the review we will point towards promising future developments.