This review discusses the important contribution made by one particular theoretical model of reading--the dual route model--to the identification and understanding of different varieties of developmental dyslexia. The model itself is first outlined, and the particular types of reading disorder that would be predicted to occur based on this model are described. The evidence for the existence of these patterns of reading disability is then reviewed and advances that have been made in understanding their basis and aetiology are described. Finally, some suggestions are made about how best to take research on heterogeneity in developmental dyslexia forward, moving away from distinct subtypes and more towards model-based reading profiles. (Contains 1 figure.)