Even though individuals generally become homeless after living in an impoverished but domiciled “vulnerable” state, few quantitative investigations consider determinants of the decline from vulnerability. This leaves in question the rather common claim that personal deficits are direct determinants of the lack of a domicile. Using data on a sample from Chicago, the study tests whether homeless and vulnerable domiciled individuals are differentiated by three sets of deficits: alienation, disabilities, and occupational deficiencies. It also assesses whether the loss of a domicile reflects a lack of access to support offered by social institutions. Variables representing lack of access are found to be the best predictors, but certain deficits have limited importance in specific subsamples. The generally limited role of deficits, in turn, seems to occur because the most problem ridden adults are protected from homelessness and from vulnerability. Differentials across gender as well as previous homeless history are also noted and explained.