Data drawn from 3 cycles of data collection for the International Adult Literacy Survey (IALS) were analyzed to identify the levels and distributions of literacy skills in the adult populations of 20 countries. The following were among the main conclusions: (1) in 14 of the countries, at least 15% of all adults have literacy skills at only the most rudimentary level, making it difficult for them to cope with the rising skill demands of the information age; (2) low literacy skills are found not just among marginalized groups but also among significant portions of the adult populations in all 20 countries; (3) educational attainment is the most important predictor of literacy proficiency; (4) higher levels of literacy skills in the work force are associated with larger proportions of knowledge jobs in the economy. (The end-of-chapter reference lists contain 82 references. Fifty tables/figures are included. Appendixes, constituting approximately 50% of the document, contain the following: (1) definitions of literacy performance on three scales; (2) discussion of the survey's methodology and data quality; (3) notes on the international comparability of IALS data; (4) data values for the figures; (5) the source database for the IALS; and (6) lists of principal participants in the project.) (MN)