Although theories of career decision making and guidance are usually offered as a basis for practice, the linkage between such theories and the practices of counselors is not always clear. Since treatment in a private dyadic context is difficult to observe and classify, public treatments such as workbooks or computerized systems are more useful for examining theoretical issues. Despite its association with the Armed Services Vocational Aptitude Battery (ASVAB) and the Department of Defense, the workbook "Exploring Careers: The ASVAB Workbook" was developed to help all high school juniors and seniors make informed and rational career decisions in both civilian and military settings. This report presents information on the ASVAB workbook based on research and development carried out over many years at Educational Testing Service. It considers issues such as: (1) why one structure and not another was used for individual assessment and for occupational information; (2) what procedures were followed to obtain, analyze, and interpret occupational information; (3) what model of career decision making was used; and (4) what evidence there is that students can handle the concepts. An overview of the model of career decision making is presented. A section on self-assessment defines the particular structure of each domain in assessment for career decision making and describes the derivation of the dimensions that it comprises. Sources and analyses of occupational information are presented and design features are described. (NB)