Protective custody inmates are defined as those persons in custody who have experienced a desire to be segregated from the general population of a prison for the purpose of securing their own protection from other inmates. This paper reviews and critiques the existing research on protective custody and other forms of dissociation. An uncritical reliance on official statistics has caused past research to underestimate the size of Canada's protective custody population. Recent Canadian research has also failed to appreciate the social dynamics of the protective custody process. One consequence of this methodological reductionism has been a generation of ineffective reform efforts intended to reduce the size of the protective population and to alleviate the plight of those inmates who fear victimization by other inmates. The author argues that the problems facing protective custody inmates -- or any inmates fearing victimization from other inmates -- must be understood as a manifestation of informal processes of social differentiation which contribute to the creation of order within contemporary penal institutions. 28 references, 6 notes. (Author abstract modified)