The origins of the international adult literacy assessment program, which began with the International Adult Literacy Survey (IALS) and continues with PIAAC, lie to a large extent in the pioneering work of national adult literacy assessments undertaken in the United States and Canada in the early 1990s.
Surveys such as the National Adult Literacy Survey (NALS) in the United States demonstrated that it was possible to combine advances in large-scale assessment with household survey methodology. Conducted in 1992 by the National Center for Education Statistics (NCES), the NALS assessed a nationally representative sample of 13,600 adults residing in households and prisons. More information about NALS can be found here.
In 2003, NCES conducted its largest national household assessment of adult literacy skills in the United States: the National Assessment of Adult Literacy (NAAL). NAAL sampled over 19,000 adults representing the entire population of the U.S. adults aged 16 and older residing in households and federal and state prisons. Both the NALS and NAAL presented a snapshot of the condition of literacy for the U.S. population as a whole and among key population subgroups, as well as changes in literacy over the proceeding decade. More information about NAAL can be found here.
The IALS study, developed by Statistics Canada and ETS in collaboration with participating national governments, adopted and refined the NALS methodology, scales and literacy frameworks. Twenty-two countries administered the IALS study in three waves between 1994 and 1998. More information about IALS can be found here.
Concurrent with the further waves of IALS data collection, Statistics Canada sponsored work on the development of a successor to IALS with the goal of measuring a broader range of adult skills than had been previously covered in IALS. The Adult Literacy and Lifeskills Survey (ALL) sought to improve on IALS by developing standards and quality assurance measures that would minimize sources of survey variability, and therefore render the survey results more comparable. Eleven countries administered the ALL study in two waves between 2003 and 2008. More information about ALL can be found here.
PIAAC seeks to ensure continuity with these previous surveys, expand on their quality assurance standards, extend the definitions of literacy and numeracy, present the problem-solving domain to emphasize skills used in technology-rich environments, and provide more information about individuals with low levels of literacy by assessing reading component skills.