The work of the United States Civil Service Commission's Personnel Research and Development Center to develop a basis for the written test portions of the Professional and Administrative Career Examination (PACE) is described. The objective was the identification of a construct-valid set of cognitive ability tests for entry level positions. Twenty-seven representative occupations were selected for intensive study, and the duties of these occupations were rated by experts for importance and time spent in their performance. A set of 31 knowledges, skills, abilities, and other worker characteristics (KSAO's) were also rated with respect to these occupations. Finally, a set of six cognitive abilities were selected by personnel psychologists for further study. Weights for these six abilities were then established for each of the 27 occupations. The ratings and the weighting system were studied to form seven occupational groups. Finally, a total of 120 occupations were assigned to these seven groups by subject matter experts on the basis of similarity of KSAO's. (Author/CTM)