Psychologists occasionally study eminent individuals, such as Nobellaureates, 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, cross-sectional versus longitudinal, micro versus macroanalytical 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. (Contains 1 table and 2 footnotes.)