To investigate the relationship between the presence of language disorder, type of epilepsy, and epileptic seizures in childhood, language levels, types of language impairment, and aetiologies were examined in 109 children, aged between 5 and 17 years, attending a national children's epilepsy assessment unit over a 4-year period. There were 70 males and 39 females. Median age was 11 years 4 months (range 5 to 18 years 9 months). In addition to neurological assessment, simultaneous video and EEG monitoring and prolonged ambulatory EEG, each child underwent a comprehensive series of multidisciplinary tests, including intelligence, language, and communication assessments. Classification of seizures and epilepsy syndromes was agreed in conference by a physician specializing in childhood epilepsies, a paediatric neurologist, and a neuropsychiatrist. Other test procedures were administered by a speech and language pathologist with assistance from a neuropsychologist when relevant. Level of language disability in these children was associated with a range of aetiological factors. Evidence was found of a significant number of associations between focal epilepsies, certain seizure types, and language disorder. Of the 46 (42.2%) children with language disorders in the research sample, 30 had localization-related epilepsies and a further three had epilepsies which were undetermined as to whether focal or generalized. Children with focal epilepsies were 30% more likely to have language disorder than other language disability subtypes. The research demonstrated a clear though often subtle association between focal (localization-related) epilepsy and language disorder, indicating an increased risk in this patient group. Children with simple or complex partial seizures were more likely to have language disorder than other language disability subtypes; they also tended to have the lowest number of seizure types per case. This is of importance to clinicians managing children with epilepsy and has implications for their educational and social welfare.