The present study investigated whether the members of adolescents' peer groups are similar in reading and spelling disabilities and whether this similarity contributes to subsequent school achievement and educational attainment. The sample consisted of 375 Finnish adolescents whose reading and spelling disabilities were assessed at age 16 with the Finnish dyslexia screening test. The students also completed a sociometric nomination measure that was used to identify their peer groups. Register information on participants' school grades also was available, and educational attainment in secondary education was recorded 5 years after completion of the 9 years of basic education. The results revealed that the members of adolescent peer groups resembled each other in reading disabilities but not in those of spelling. Reading disabilities and academic achievement shared within the peer group also contributed to educational attainment in secondary education. Finally, reading disabilities played a larger role in educational attainment among males than among females. (Contains 2 figures and 4 tables.)