This article describes the initial research associated with a new approach for measuring McClelland's trichotomy of needs. The new approach is based on behavioral decision theory and involves modeling an individual's decision-making behavior to determine how the person weighted his need for affiliation (« Aff), need for power (n Pow), and need for achievement (n Ach) in arriving at decisions. Three population groups—161 scientists and engineers, 149 Air Force officer graduate students, and 94 management executives—were involved in the initial validation effort. All eight hypotheses concerning intergroup and intragroup relationships and concurrent validity issues were supported by the empirical data. The dominant motive for scientists and engineers and graduate students was n Ach, whereas n Pow was dominant for management executives. Scientists and engineers and graduate students had higher n Ach scores than management executives, who had the highest n Pow scores. Student grade point average correlated with n Ach and officer performance scores correlated with n Pow. Scientists and engineers who published had higher n Ach scores than those who did not. The new approach, which requires further research and validation, suggests a new methodology for researchers of McClelland's needs.