In 2002-03, approximately 68.5 million people, or one-third of civilian, non-institutionalized adults age 16 and older in the United States, took formal courses or training that were not part of a traditional degree, certificate, or apprenticeship program for reasons related to their job or career. This Issue Brief examines these adult learners' reasons for participation in such formal, work-related courses. While much information about adults enrolled in college/university and vocational/technical credential programs is available from institution-based surveys, less is known about participation in formal courses outside of these traditional programs, such as those offered by an employer. Research suggests that there has been an increased demand for work related adult education, resulting from changes in the labor market, technology, and management practices. These changes have placed new demands on workers, who increasingly are expected to assume multiple responsibilities, handle changing procedures, and use a broad base of knowledge on the job. It was found that more than 90 percent of adults who took formal work-related courses in 2002-03 reported doing so in order to maintain or improve skills or knowledge they already had, while fewer than 20 percent took such courses to get or change a job or career field. Among employed adults, the majority took courses because their employer required or recommended participation, while about a fifth did so in order to get a promotion or pay raise. The likelihood of taking classes for the selected reasons examined in this brief generally varied by participants' age, education, employment status, occupation, and household income.