The IALS study was based on a powerful theory of adult reading, a theory that served as a basis for both the design of the assessment and the interpretation of the resultant data. Thus, IALS afforded researchers a unique opportunity to empirically validate the theory with data of unparalleled coverage and large, representative samples of adults. The ALL offers a much greater potential to shed empirical light on the validity of several of the various competing frameworks which deal with the organisation and structure of human intelligence and cognition.2 A long term objective is, therefore, to assure that the ALL data is made available to researchers for this purpose, particularly those researchers involved in the ongoing work of the OECD's DeSeCo project.

• To foster continued international co-operation on the design, implementation and analysis of data on the distribution and co-variates of skill

Direct measurement of the sort employed in the IALS study requires considerable operational and technical skill and significant financial resources to unilaterally design, validate, collect and analyse. Such resources are beyond the means of many of even the most advanced economies to support. IALS has also demonstrated the potential of a comparative perspective to shed light on deep relationships underlying the observed phenomena, relationships that remain undetected in idiosyncratic national studies. 2. See for example, Toward a triarchic theory of human intelligence, Robert J. Sternberg, 1984 Cambridge University Press, 1984 and Frames of Mind: The Theory of Multiple Intelligences, Howard Gardner, Harper Collins, 1993.