Cultural identity is a construct from the literature on Minority Identity Development Theory. One's cultural identity provides one means of understanding one's psychological relationship to cultural communities with which one has ties. A new paradigm has been presented for understanding deafness as a cultural difference rather than a medical pathology. To draw out one implication of this new paradigm, a theory is presented for how audiologically deaf people develop culturally Deaf identities. Four stages of cultural identity development are described. Culturally hearing refers to people who hold the dominant culture's attitudes and beliefs about deafness. Culturally marginal refers to people who experience shifting loyalties or profound confusion regarding their relationship to the Deaf and hearing worlds. Immersion identity refers to a radical or militant Deaf stance. Bicultural deaf people have integrated their Deaf pride in a balanced way into their full humanity. Different paths of development are outlined dependent on the circumstances surrounding the hearing loss. An instrument, the Deaf Identity Development Scale (DIDS) is developed in both English and American Sign Language to measure Deaf cultural identity. The DIDS is administered to 161 subjects: 105 students from Gallaudet University and 56 members from an organization of late deafened adults. Support for the existence of the four distinct kinds of cultural identity is provided by acceptable reliability, interscale and item-to-scale correlations. Thirteen hypotheses pertaining to instrument construction and theory and test validity are tested. Test results are used to illuminate further the paths of deaf identity development. Suggestions for improvement in the DIDS are presented.