Understanding cognitive research on the integration of 2 languages in bilingual memory is difficult because of the different terminology, methodology, analysis, and interpretation strategies that scholars with different backgrounds bring to the research. These studies can be usefully categorized on 2 dimensions: memory for verbal experience versus linguistic knowledge, and systemwise versus pairwise issues. Experimental findings in this area converge on the conclusion that at the word meaning/ conceptual level, both episodic and linguistic memory can be characterized as shared at the systems level and at least partly shared at the pairwise translation-equivalent level. Interpretation problems that stem from weak hypothesis testing structure and from covert translation can be minimized by using appropriate design and analysis techniques.Simply put, bilingualism, or using two languages to communicate, is a tool that allows people with different languages to exchange information. A biblical account of the origin of the world's many languages is given in the Old Testament story of the Tower of Babel, where it is written that God divided the tower's builders by giving them different languages. Without a common language with which to communicate, the builders failed in their goal of constructing the tower. Ironically, a similar situation has arisen in research on bilingualism in that researchers may be lacking a common language. This division has come about not because of any divine intervention but because researchers talk about the phenomena differently or "speak different languages," thereby introducing confusion in the research community. A translator is needed to clarify the links between these different research languages to assist researchers in understanding one another and to facilitate the building of research in this field.Cognitive psychologists, especially those with an informationprocessing perspective, try to clarify the organization of the mental representations and processes involved in thought. These representations and processes are, of course, fundamental to the structure and processes of language as well. An important debate relating to bilingualism focuses on whether two languages access one common or two separate conceptual systems. A cursory reading of the literature would suggest that there is evidence for both views. In this review, however, we see that the preponderance of evidence favors a single conceptual system and that there is little if any evidence to the contrary. Unfortunately, the data from many A preliminary version of this article formed part of my doctoral dissertation completed at the University of California, Los Angeles. I especially thank Nancy Henley for her comments, suggestions, and discussions through the early stages of this project. Thanks also to Tom Wickens, Ward O'Neill, and Allan Paivio for their helpful comments on previous versions of the manuscript and to John Gabrieli for making resources available for its completion.Correspondence concerning this article shoul...