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2Laboratory designs and paradigms: Words, sounds, and sentences In the past 10-15 years there has been a notable increase in the number of studies that take a psycholinguistic or cognitive approach to bilingualism. Although there is a long history of research on issues such as whether there is a critical period1 for second language acquisition (see Birdsong, 1999, for a review), it is only recently that cognitive scientists have begun to see that bilingualism is the norm for most of the world’s population. Because cognitive science seeks to identify universal properties of thought, the bilingual has become a model subject of study rather than a marked case. Researchers have come to see that studies of bilingual cognition provide critical evidence regarding the principles that constrain or permit interactions across cognitive systems. At the same time, the development of a set of laboratory tools to investigate language performance and its neurocognitive basis have enabled a new experimental approach to bilingualism that is informed by studies of cognitive processing and brain function, in addition to the linguistic approaches that have traditionally characterized bilingual research. What do bilinguals tell us about cognition? And what can cognitive approache