Some of these groups include homeless persons, the chronically mentally ill, school dropouts, criminal offenders, prostitutes, and juvenile offenders. Individuals who belong to these hidden populations are often at greater risk of drug abuse and drug-related morbidity than the general population. The first set of papers presents overviews and historical perspectives on ethnography and qualitative science. This is followed by a section focusing on methodological issues in ethnography including snowball sampling, inductive analysis, and ethnographic field stations. The final section presents actual case studies in which ethnographical techniques were applied to the study of drug using behaviors. Chapter references