For most people in the United States, quality postsecondary credentials--which include two- and four-year college degrees, vocational training certificates, and professional licenses--offer the most direct path to economic and social mobility. In fact, 80 percent of today's jobs require more than a high school degree. Yet as of 2019, about 115.3 million U.S. adults ages 16-64 did not have a postsecondary credential. About one in five of these adults (23.9 million) were immigrants. As the U.S. economy seeks to adapt to forces such as population aging and technological change that are reshaping the labor market, much will depend on how well the United States trains and utilizes its available workforce. Immigrants are an important, but often overlooked, target for initiatives seeking to increase the number of credential holders. Including them more fully would help fill gaps in the labor force, expand local economies, and address racial/ethnic disparities in credential access and attainment given that nearly three-quarters of immigrants without postsecondary credentials are Latino or Black. This issue brief uses MPI's unique methodology for assigning legal status to immigrants in the U.S. Census Bureau's American Community Survey to explore the characteristics of adults without postsecondary credentials, broken down by U.S. citizenship and legal status. In doing so, it highlights characteristics that can make credential acquisition more straightforward or more challenging and that should be taken into account in policies and programs that aim to promote workforce development and economic mobility.