Background:Convulsive status epilepticus is the mostcommon childhood medical neurological emergency,and is associated with significant morbidity and mortality. Mostdata for this disorder are from mainly adult populations and might not be relevant to childhood. Thus we undertook the North London Status Epilepticus in Childhood Surveillance Study (NLSTEPSS):a prospective,population-based study of convulsive status epilepticus in childhood,to obtain a uniquely paediatric perspective.Methods:Clinical and demographic data for episodes of childhood convulsive status epilepticus that took place in north London were obtained through a clinical network that covered the target population. We obtained these data from anonymised copies of a standardised admission proforma; accident and emergency,nursing,ambulance,and intensive-care unit notes; and interviews with parents,medical,nursing,and paramedic staff. We investigated ascertainment using capture-recapture modelling.Findings:Of 226 children enrolled,176 had a first ever episode of convulsive status epilepticus. We estimated that ascertainment was between 62%and 84%.The ascertainment-adjusted incidence was between 17 and 23 episodes per 100 000 per year. 98 (56%,95%CI 48-63) children were neurologically healthy before their first ever episode and 56 (57%,47-66) of those children had a prolonged febrile seizure. 11 (12%,6-18) of children with first ever febrile convulsive status epilepticus had acute bacterial meningitis. Conservative estimation of 1-year recurrence of convulsive status epilepticus was 16%(10-24%). Case fatality was 3%(2-7%). Interpretation:Convulsive status epilepticus in childhood is more common,has a different range of causes,and a lower risk of death than that in adults. These paediatric data will help inform management of convulsive status epilepticus and appropriate allocation of resources to reduce the effects of this disorder in childhood. Background: Convulsive status epilepticus is the most common childhood medical neurological emergency, and is associated with significant morbidity and mortality. Thus we undertook the North London Status Epilepticus in Childhood Surveillance Study (NLSTEPSS): a prospective, population-based study of convulsive status epilepticus in childhood, to obtain a uniquely pediatric perspective. Methods: Clinical and demographic data for episodes of childhood convulsive status epilepticus that took place in north London were obtained through a clinical network that covered the target population. We obtained these data from anonymised copies of a standardized admission proforma; accident and emergency, nursing, ambulance, and intensive-care unit notes; and interviews with parents, medical, nursing, and paramedic staff. ascertainment using capture-recapture modeling. Findings: Of 226 children en rolled, 176 had a first ever episode of convulsive status epilepticus. We estimated that ascertainment was between 62% and 84%. ascertainment-adjusted incidence was between 17 and 23 episodes per 100 000 per year. 98 (56%, 95% CI 48-63) children were neurologically healthy before their first ever episode and 56 (57%, 47-66) of those children had a prolonged febrile seizure. 11 (12%, 6-18) of children with first ever febrile convulsive status epilepticus had acute bacterial meningitis. Conservative estimation of 1-year recurrence of convulsive status epilepticus was 16% (10-24%). Case fatality was 3% (2-7%). Interpretation: Convulsive status epilepticus in childhood is more common, has a different range of causes, and a lower risk of death than that in adults. These pediatric data will help inform management of convulsive status epilepticus and appropriate allocation of resources to reduce the effects of this disorder in childhood.