In the wake of the technological revolution that began in the last decades of the 20th century, labour market demand for information-processing and other high-level cognitive and interpersonal skills is growing substantially. The Survey of Adult Skills, a product of the OECD Programme for the International Assessment of Adult Competencies (PIAAC), was designed to provide insights into the availability of some of these key skills in society and how they are used at work and at home. The first survey of its kind, it directly measures proficiency in several information-processing skills – namely literacy, numeracy and problem solving in technology-rich environments. The Survey of Adult Skills: Reader’s Companion, Second Edition describes the design and methodology of the survey and its relationship to other international assessments of young students and adults. It is a companion volume to Skills Matter: Further Results from the Survey of Adult Skills. Skills Matter reports results from the 24 countries and regions that participated in the first round of the survey in 2011-12 (first published in OECD Skills Outlook 2013: First Results from the Survey of Adult Skills) and from the nine additional countries that participated in the second round in 2014-15 (Chile, Greece, Indonesia [Jakarta], Israel, Lithuania, New Zealand, Singapore, Slovenia and Turkey).