Psychologists occasionally study eminent individuals, such as Nobel laureates, U.S. presidents, Olympic athletes, chess grandmasters, movie stars, and even distinguished psychologists. Studies using such significant samples may be differentiated along 7 distinct dimensions: qualitative versus quantitative, single versus multiple case, nomothetic versus idiographic, confirmatory versus exploratory, crosssectional versus longitudinal, micro versus macro analytical units, and direct versus indirect assessments. However, the vast majority of psychological inquiries may be clustered into just 4 types: historiometric, psychometric, psychobiographical, and comparative. After presenting the intrinsic and extrinsic justifications for studying famous persons, the main methodological issues concerning sampling, measurement, and analysis are discussed. The future prospects of significant samples in psychological research are then briefly examined.Empirical journal articles in psychology almost invariably commence their methods section with a subsection in which the researchers define the "subjects" or "participants" of the study (American Psychological Association, 1994). This sample specification comes first because all subsequent procedures and analytical strategies are usually contingent on that choice. An experimental manipulation or psychometric instrument that is indubitably appropriate for one sample might be manifestly inappropriate for another (e.g., whether to use an intelligence test designed for children or adults). In psychology, this sample description is especially critical. Few sciences feature the same diversity of entities that might serve as subjects in psychological research: human beings of every age, gender, ethnicity, occupation, and capacity; animals ranging from mammals, birds, and fish to insects, mollusks, and worms. Yet as diverse as these various subject pools may be, they all seem to have one thing in common: The individuals that compose This article is based on a paper read at the Internationa!