SUMMARYPurpose: This study examined the severity and range of linguistic impairments in young, intermediate, and adolescent youth with epilepsy and how these deficits were associated with illness effects, nonverbal intelligence, psychopathology, and reading. Methods: Tests of language, intelligence, achievement, and structured psychiatric interviews were administered to 182 epilepsy youth, aged 6.3-8.1, 9.1-11.7, and 13.0-15.2 years, as well as to 102 age-and gender-matched normal children. Parents provided demographic, seizure-related, and behavioral information on their children. Results: Significantly more epilepsy subjects had language scores 1 standard deviation (SD) below average than the age-matched control groups did. The intermediate and adolescent epilepsy groups also had significantly lower mean language scores compared to their matched controls. The older compared to the younger epilepsy groups had more language impairment and a wider range of linguistic deficits. Longer duration of illness, childhood absence epilepsy, psychiatric diagnosis, and socioeconomic status were associated with linguistic deficits in the young group. Prolonged seizures, lower Performance IQ, and minority status predicted low language scores in the intermediate epilepsy group. In the adolescent group, language impairment was associated with poor seizure control, decreased Performance IQ, and lower socioeconomic status. Linguistic and reading deficits were significantly related in each epilepsy group. Conclusions: The age-related increase in linguistic impairment, different profiles of predictors in each age group, and the relationship of linguistic deficits with poor reading skills have important clinical, developmental, theoretical, and academic implications.