A concern with the motivational behavior for keeping up-to-date, a learning process, is presented. The half-life of a professional's competence is described as the time after completion of professional training when, because of new developments, practicing professionals have become roughly half as competent as they were upon graduation to meet the dmnds of their profession. A questionnaire was developed that would enable practicing resource managers and scientists to supply as much information as possible on their updating needs. On the basis of 5,600 responses, five determiners of adult motivation were ranked by the natural resource managers in the following order: personal ambition and goals, on-the-job problem solving, organizational climate, discussion with colleagues, and supervisor. One of the principal recommendations emerging from the study is that managers should be spending one day a week or the equivalent in regularly scheduled study or training. (Author/CK)