There is a strong and growing argument for higher educational attainment in the United States. The jobs that are expected to support the economy in the coming years will depend on a skilled workforce that is able to learn and adapt quickly to new challenges. However, demographic patterns demonstrate that relying on the traditional K-16 pipeline to meet the educational and workforce needs of the states and the nation will not be enough. In addition, the economic and personal benefits that individuals gain from education also argue for greater focus and emphasis on adult learning. Yet not enough is known or publicized about the scope and potential of adult learning in the U.S. or about the barriers to adult participation. While many colleges and universities have entered the market for adult students, and while some enlightened corporations have encouraged participation in education among their front-line employees as a strategic investment, both federal and state policy remain largely concerned with the traditional educational pipeline. While the major purpose of this report is to present what is known about adult participation in education nationally and across the fifty states, a secondary purpose is to highlight what is not known. The nation faces significant gaps in available data about adult participation in many areas. For example, not all 50 states have data on the degrees and certificates granted to adults, enrollment by adults in noncredit programs as a proportion of all adults in the population, college-going rates, GED (General Educational Development) recipients, participation in distance learning by age group, or progression by level through basic literacy training. Addressing these data gaps in order to gain a better understanding of education levels and patterns of learning for all citizens and members of the workforce should be a priority in state and national policymaking over the next decade. Yet the data people already have can be instrumental in focusing a state's attention on adult learning and workforce development. An important first step for states will be to relate the data they have to the factors that influence enrollment figures and educational attainment outcomes, such as the state's workforce demographics, local and state economies, state policies and funding. Understanding what underlies the data can help state policymakers identify priorities for state action and use limited resources in the most effective and efficient manner. (Contains 68 figures and 4 tables.)