This chapter presents the basic rationales for the use of the social survey, which-because of its wide popularity among contemporary sociologists-deserves special attention. All six basic types of survey designs share the following features: the use of interviewing and/or questionnaires as the major mode of data collection; collection of data from large numbers of persons; and the use of multivariate analysis as the major method of data analysis. They vary by the presence or absence of the following: randomization; comparison groups created before or after data collection; repeated observations of the same or equivalent groups. The deficiencies and flaws of the social survey have been extensively discussed and were found to revolve around internal and external validity, treatment of interaction, circumscribed time period, aggregate-individualistic bias, and failure to approximate the experimental model, thereby jeopardizing causal inferences.