To understand the complex relations between language and learning, we have to look at both how children learn language and what it is that they learn that allows them to communicate with others. To accomplish this, we need to distinguish between apparent differences in language that are related to the modality of communication and actual differences in language fluencies observed among deaf children. It also will help to examine some relevant differences between deaf children and hearing children. We have already pointed out that the distinction between spoken language and sign language, while a theoretically important one for researchers, is an oversimplification for most practical purposes. It is rare that deaf children are exposed only to spoken language or sign language, even if that is the intention of their parents or teachers. According to 1999 data, approximately 55 percent of deaf children in the United States are formally educated in programs that report either using sign language exclusively (just over 5 percent) or signed and spoken language together (just over 49 percent) (Gallaudet University, Center for Applied Demographic Statistics). Because almost half of all deaf children in the United States are missed in such surveys, however, these numbers only should be taken as approximate. Comparisons of the language abilities of deaf children who primarily use sign language with those who primarily use spoken language represent one of the most popular and potentially informative areas in research relating to language development and academic success. Unfortunately, this area is also one of the most complex. Educational programs emphasizing spoken or sign language often have different educational philosophies and curricula as well as different communication philosophies. Programs may only admit children with particular histories of early intervention, and parents will be drawn to different programs for a variety of reasons. Differences observed between children from any two programs thus might be the result of a number of variables rather than, or in addition to, language modality per se. Even when deaf children are educated in spoken language environments, they often develop systems of gestural communication with their parents (Greenberg et al., 1984).