We review current knowledge about reading development and the origins of difficulties in learning to read. We distinguish between the processes involved in learning to decode print, and the processes involved in reading for meaning (reading comprehension). At a cognitive level, difficulties in learning to read appear to be predominantly caused by deficits in underlying oral language skills. The development of decoding skills appears to depend critically upon phonological language skills, and variations in phoneme awareness, letter-sound knowledge and rapid automatized naming each appear to be causally related to problems in learning to read. Reading comprehension difficulties in contrast appear to be critically dependent on a range of oral language comprehension skills (including vocabulary knowledge and grammatical, morphological and pragmatic skills).
Keywords: causes; decoding; dyslexia; intervention; reading; reading comprehension impairment.