To promote leadership research on managers' motivation, a measurement (Andersen Motivation Profile Indicator [AMPI]) has been developed and tested that (a) measures achievement, affiliation, and power motivation; (b) measures the relative strengths of these factors; (c) rests explicitly on the definitions of McClelland; and (d) measures managers' work motivation. The questionnaire has been tested for reliability and validity with responses from 580 managers. The application of the instrument in four studies with responses from 565 managers in other organizations supported McClelland's theoretical claims: (a) managers have motivation profiles, (b) there are differences in motivation profiles between managers across organizational types, (c) there are no significant differences in motivation profiles between female and male managers, and (d) managers who are predominantly power motivated enhance organizational effectiveness. Arguably, the application of the instrument may be an indicator of its quality. The instrument facilitates leadership research on the relationship between managers' motivation profiles and organizational specifics, gender, sociocultural factors, and organizational outcomes.