Construct validity of reading measures in adults with significant reading difficulties.

The four studies of adult literacy in this special issue of the Journal of Learning Disabilities address measurement issues in adult populations and the relation (by comparison) of similar studies of childhood literacy. Despite differences in selection criteria, tests, and research questions, there is some convergence across studies, especially on construct validity issues. It is reassuring to see evidence of construct invariance across children and adults. The examples of lack of convergence relative to childhood literacy studies are instructive, and investigators should be careful not to extrapolate directly from child to adult models.