Concerns have been raised about variation in care quality and outcomes among children and young people with epilepsies in England. We aimed to investigate the association between quality of paediatric care, hospital admissions, and all-cause deaths among epilepsy patients. In this longitudinal data linkage study of paediatric epilepsy services in England, we linked unit-level data from round 1 (2009-11) and round 2 (2013-14) of the Epilepsy12 national clinical audit, with death registrations from the UK Office for National Statistics and data for unplanned hospital admissions from Hospital Episode Statistics. We investigated the association between unit-level performance in involving a paediatrician with epilepsy expertise, an epilepsy specialist nurse, and a paediatric neurologist (where appropriate) in round 1 and the proportion of adolescents (aged 10-18 years) with epilepsy admitted to each unit who subsequently died during the study period (April 1, 2009, to March 31, 2015). We also investigated whether change in Epilepsy12 performance between the two audit rounds was associated with changes in the standardised ratio of observed-to-expected unplanned epilepsy admissions over the same period. In 99 units with data for the analyses relating to paediatricians with epilepsy expertise and epilepsy specialist nurses, 134 (7%) of 1795 patients died during the study period, 88 (5%) of whom died after the transition to adult service. In 55 units with data for the analyses relating to paediatric neurologists, 79 (7%) of 1164 patients died, 54 (5%) of whom did so after the transition. In regression models adjusting for population, unit, and hospital activity characteristics, absolute reductions in total mortality risk (6·4 percentage points, 95% CI 0·1-12·7) and mortality risk after transition (5·7 percentage points, 0·6-10·8) were found when comparing units where all versus no eligible patients were seen by a paediatric neurologist. Units where all eligible patients were seen by a paediatric neurologist were estimated to have absolute reductions of 4·6 percentage points (0·3-8·9) in total mortality and of 4·6 percentage points (1·2-8·0) in post-transition mortality, compared with units where no or some eligible patients were seen by a paediatric neurologist. There was no significant association between performance on being seen by an epilepsy specialist nurse or by a paediatrician with epilepsy expertise and mortality. In units where access to an epilepsy specialist nurse decreased, the standardised ratio of epilepsy admissions increased by a mean of 0·21 (0·01-0·42). Among adolescents with epilepsy, greater involvement of tertiary specialists in paediatric care is associated with decreased all-cause mortality in the period after transition to adult services. Reduced access to an epilepsy specialist nurse was associated with an increase in paediatric epilepsy admissions. The Health Foundation.