A number of factors have come together to generate a renewed interest in adult learning in Organization for Economic Cooperation Development (OECD) countries, including emphasis on demand shifts associated with technology and globalization; large size of skills needs; and aging population. Major gaps in knowledge about adult learning still hinder effective diagnosis and policymaking. What is encompassed by "adult learning" is not clearly defined. Statistical evidence on reasons why adults participate in learning is negative; more is known about what does not work than what does. Participants are more likely to be already well-educated or well-trained individuals. Too, the benefits of adult learning are not always clear. On the policy side, the OECD does not know how transposable good practices in adult learning are between countries. It needs to be able to identify not only what works, but for whom, and in what circumstances. The OECD work program is working on both the quantitative and qualitative aspects of adult learning. On the quantitative front, the OECD is involved in preparing new data collections on assessments of adult skills. On the qualitative side, it is involved in the Definition and Selection of Competencies project that aims to identify key competencies needed in the workplace and society and is analyzing policy options and practices under the umbrella of the Thematic Review of Adult Learning. (YLB)