This is a critical review of the extensive and complex research literature on developmental dyslexia as it might apply to adults participating in courses which offer literacy, numeracy, and English for speakers of other languages (ESOL). By using electronic databases, including the Science Citation and Social Science Citation Indexes, ERIC and Medline, by making visual inspections of library holdings at the Institute of Education, University of London and elsewhere and by searching the Internet, we identified a large number of potentially relevant book chapters or papers published in peer-reviewed journals. Although we set our watershed at 1987, we included earlier items when continuing citation underlined their importance. From more than three thousand items initially identified, we selected 1,800 items for inspection. We obtained reprints or made photocopies of 1,220 items, which we then read and annotated. Because very few of the items deal specifically and exclusively with adults and even fewer dealt with adults in basic education, we have needed to make cautious inferences from the literature on childhood dyslexia. In our review, we consider the major explanatory theories of dyslexia and their implications for practice. We also consider some recent alternative perspectives on developmental reading difficulties. A draft version was reviewed by a panel of academic experts and this version incorporates nearly all of their suggested amendments and additions. We conclude that there is no evidence from research to support a policy of differentiating dyslexic from non-dyslexic students in adult literacy, numeracy and ESOL.