Both within and beyond the OECD region, governments and other stakeholders are increasingly interested in the assessments of the skills of their adult populations in order to monitor how well prepared they are for the challenges of the knowledge based society. The current paper provides an overview of the two international assessments of adult literacy which have already taken place in the OECD region - the International Adult Literacy Survey (IALS) and the Adult Literacy and Life Skills Survey (ALL) as well as of the forthcoming OECD Programme for the International Assessment of Adult Competencies (PIAAC). The conceptual framework for the assessments is described with a focus on the links between the different assessments. In addition, the paper provides a survey of the outputs of IALS and ALL including a review of the major themes addressed in the literature which has used data from these surveys as well as a brief discussion of their policy impact.