This entry discusses the concept of representativeness and its importance in social and behavioral science research. In conducting such research, it is desirable but usually not possible to study an entire population; in consequence, researchers sample from the population and then generalize findings of the research based on the sample to the population. The analytic sample is thus supposed to represent the population. It is important to know whom a study sample represents to evaluate implications of the study and findings. Who is represented in a study’s sample frames the study.