Participant observation is a commitment to adopt the perspective of those studied by sharing in their day-to-day experiences. The participation may be known to those observed, such that it is clear they are being studied, or the investigator may conceal his scientific role and attempt to become a "normal" member of the community, cult, organization, tribe, or club being studied. This chapter discusses that participant observation may be most profitably treated as a method of qualitative analysis that requires observer submersion in the data and the use of analytic induction and theoretical sampling as the main strategies of analysis and discovery. The observer as participant role is one in which investigations typically include only one visit, or interview, with the respondent. Subject maturation reflects a dimension that is particularly important in participant observation, because the investigator will be establishing relationships that will lead to changes in the subjects themselves.