This article reviews research on the behavioral and molecular genetics of reading and, where available, spelling. Recent research is summarized, suggesting that reading and spelling appear to share a common genetic basis, and that dyslexia lies on a genetic continuum with normal variance in reading skill. Research also suggests that while many of the genes involved in reading disorder affect all forms of reading, some genes are specific for processing irregular words, while others are specific for non-word or grapheme-phoneme processing, forming a genetic basis for the clinical distinction between surface and phonological dyslexia. Advances in molecular genetics mean that identifying specific genes for reading is now a practical project, and to date 11 chromosomal regions have been associated with reading or spelling and these findings are reviewed. Finally data are presented on the genetic relationship of dyslexia to other developmental disorders including Autism and ADHD, and reasons for this overlap or comorbidity are discussed. Gene discovery is at a point where precise biochemical effects underlying dyslexia can be understood, findings that will have an important impact not only for neuropsychology and neuroscience but also for psychological practice. (Contains 2 figures.)