The "Program for the International Assessment of Adult Competencies" (PIAAC) is a cyclical, large-scale study of adult skills and life experiences focusing on education and employment. Nationally representative samples of adults between the ages of 16 and 65 are administered an assessment of literacy, numeracy, and problem solving in technology rich environments, as well as survey questions about their educational background, work history, the skills they use on the job and at home, their civic engagement, and sense of their health and well-being. The results are used to compare participating countries on the skills capacities of their workforce-aged adults and to learn more about relationships between educational background and employment and other outcomes. The U.S. PIAAC National Supplement is the second PIAAC data collection in the United States. Conducted from August 2013 through April 2014, the National Supplement's household data collection surveyed 3,660 adults from three key U.S. subgroups of interest: (1) unemployed adults (age 16 to 65); (2) young adults (age 16 to 34); and (3) older adults (age 66 to 74). The National Supplement was conducted for two reasons. First, augmenting the U.S. PIAAC sample permits more in-depth analyses of the cognitive and workplace skills of the U.S. population, in particular of the three key U.S. subgroups listed above. Second, the additional information on adults age 66 to 74 and incarcerated adults makes PIAAC data comparable with data collected by NCES in the 2003 National Assessment of Adult Literacy (NAAL). This in turn makes it possible to analyze change in adult skills over the decade between the two studies. PIAAC is designed to assess adults in different countries over a broad range of abilities, from simple reading to complex problem-solving skills, and to collect information on individuals' skill use and background. PIAAC defines four core competency domains of adult cognitive skills that are seen as key to facilitating the social and economic participation of adults in advanced economies: literacy, reading components, numeracy, and problem solving in technology-rich environments. The purpose of this report is to present selected results from the first and second rounds of the U.S. PIAAC household data collection (PIAAC 2012/2014). PIAAC results are reported in two ways: (1) as scale scores (estimated on a 0-500 scale) in the three domains of literacy, numeracy, and problem solving in technology-rich environments; and (2) as percentages of adults reaching the proficiency levels established for each of these domains. PIAAC reports five proficiency levels for literacy and numeracy and four levels for problem solving in technology-rich environments. The Organisation for Economic Co-operation and Development (OECD) provides detailed descriptions of the types of skills that can be performed at each level. This report follows OECD reporting conventions by combining the top two proficiency levels for the literacy and numeracy scales. This report also provides an international average for scale scores and proficiency levels for variables that are internationally comparable. The following are appended: (1) Members of the PIAAC Subject Matter Expert Groups; (2) PIAAC Scales and Proficiency-Level Descriptions; and (3) Methodology and Technical Notes.