History of International and National Adult Literacy Assessments

The origins of the international adult literacy assessment program, which began with the International Adult Literacy Survey (IALS) and continues with Program for the International Assessment of Adult Competencies (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.

In the United States, the National Adult Literacy Survey (NALS) was conducted in 1992 by the National Center for Education Statistics (NCES). NALS assessed a nationally representative sample of adults residing in households, as well as a sample of adults in prisons. More information about NALS can be found here.

In 2003, NCES conducted its largest household assessment of adult literacy skills in the United States: the National Assessment of Adult Literacy (NAAL). NAAL sampled adults representing the entire population of U.S. adults residing in households and also sampled adults representing the population in federal and state prisons. NALS and NAAL each presented a snapshot of the condition of literacy for the U.S. population as a whole and among key population subgroups and, when looked at in combination, changes in literacy over time. 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, including the United States, 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 covered previously. 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, including the United States, administered the ALL study in two waves between 2003 and 2008. More information about ALL can be found here.

In 2022, NCES released the data with the rescaled literacy (NALS, IALS, and ALL) and numeracy (ALL) scores on the three previous studies. This data facilitates the analysis of national trend data across NALS and PIAAC and the analysis of international trend data across the three international surveys – IALS, ALL, and PIAAC. The assessment domains from these three previous studies were rescaled to match the statistical models used in creating PIAAC scores for literacy and, in the case of ALL, numeracy. Rescaling was possible because PIAAC administered a sufficient number of the same test questions used in NALS, IALS, and ALL. Rescaled plausible values for literacy for NALS, IALS, and ALL and numeracy for ALL, along with some trend background questionnaire items, allow for trend analysis with the U.S. PIAAC results. The restricted-use data files can be found on the NALS Data Files, IALS Data Files, and ALL Data Files publication pages.

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.

Overview of Previous International and National Assessments of Adult Skills