The first approaches to typologies of homeless persons were based on differing features of certain groups of homeless people, developed in part to describe the population and in part to ascribe a causal relation of these features to homelessness. Such studies, published from 1912 to the 1980s, have been reviewed by Louisa Stark (1992). Nearly all of these studies were derived from surveys of single homeless persons and were based on homeless shelter-based populations. Despite the fact that homeless people were typecast in different ways at different times, several major types were described: First, people were classified as unemployed workers, alcoholics, mentally ill, and chronically physically ill or disabled. Elderly people and “bums” constituted two additional, albeit much smaller, groups. Recognizing the heterogeneity of homeless people, Bahr and Caplow (1973) attempted to reduce this diversity to a single operational feature. They postulated a Durkheim-like concept of disaffiliation, a detachment from social roles and institutions, as a common pathway to homelessness. They distinguished three major categories of disaffiliation resulting from external changes that leave the individual with few affiliations: (1) society withdrawing from the individual in periods of economic depression, war, persecution, etc; (2) from individual choice (opting out of societal roles); and (3) handicap or lifetime “unsocialization” resulting from mental illness or other chronic disorders (Bahr and Caplow, 1973). This theory lost ground in the next 2 decades as studies showed that homeless people had a network of social roles and institutional or personal affiliations, albeit usually not with rich people.
This typological approach continued even after the growth of homelessness and changes in the homeless population that included younger homeless single people and families in the 1980s. For instance, Fischer and Breakey (1985) grouped mission users into the chronically mentally ill, the chronic alcoholic, street people, and the “situationally distressed.” Other typologies of some of these groups were subsequently published, some of which were highly disaggregated. For instance, Shepherd (2000), who used cluster analysis with a population of homeless adults, distinguished 11 profiles (malingerers, depression with alcoholism, symptom minimizers, psychotic avoiders, service avoiders, newly homeless, local ethnic minority, women with children, healthy family, other-Caucasian, and nondrug users).
The 1980s saw homelessness emerge as a major social problem, and several streams of research on the homeless population were initiated (see Institute of Medicine  and Jahiel [1992a] for reviews). The only common factor in this very heterogeneous homeless population was extreme poverty, associated with a decrease in low income housing in the late 1970s and 1980s (e.g., Calsyn and Roades, 1994). The concept of homelessness as a manifestation of extreme poverty began to replace that of homelessness as social disaffiliation. Homelessness was seen as an aggregate rather than an individual problem due to the disequilibrium between the number of poor people and the number of low-income housing units: a certain number of people had to become homeless at a given time unless the housing supply was increased, and environmental, situational, and personal characteristics determined who was most vulnerable to become part of that population (McChesney, 1992a).
Some years ago, Jahiel (1987) described a dichotomy between two types of homelessness: benign homelessness and malignant homelessness. Benign homelessness means that the state of homelessness causes relatively little hardship, lasts for a short time and does not recur soon. For these people, it is relatively easy to gain back a home and a stable tenure on that home. Malignant homelessness means that the state of homelessness is associated with considerable hardship or even permanent damage to the person who is homeless. It lasts for a relatively long time or recurs at short intervals; extraordinary efforts must be expended to gain back a home with a stable tenure, and these efforts are often unsuccessful.