It is supposed that there is an early, foundation stage in beginning readin
g during which children acquire basic letter-sound knowledge, a capability
for alphabetic processing, and a logographic sight vocabulary. An assessmen
t of foundation processes was administered to Scottish children with readin
g difficulties (n = 51) and to reading-level-matched controls (n = 56). The
results suggested that the foundation is normally in place by the time a r
eading age of about 7 years has been achieved. Foundation-level dyslexia is
identifiable in children with reading difficulty whose reading ages fall b
elow this level. Differing patterns of dyslexia were observed, depending on
whether the primary effect was on letter-sound learning (literal dyslexia)
, the acquisition of the alphabetic process (alphabetic dyslexia), or reten
tion of a sight vocabulary (logographic dyslexia). Balanced dyslexia, in wh
ich both alphabetic. and logographic functions were impaired, was also foun
d. Some implications for assessment and treatment are discussed.