Background: No seizure first aid training intervention exists for people with epilepsy who regularly attend emergency departments and their significant others, despite such an intervention’s potential to reduce clinically unnecessary and costly visits., Objectives: The objectives were to (1) develop Seizure first Aid training For Epilepsy (SAFE) by adapting a broader intervention and (2) determine the feasibility and optimal design of a definitive randomised controlled trial to test SAFE’s efficacy., Design: The study involved (1) the development of an intervention informed by a co-design approach with qualitative feedback and (2) a pilot randomised controlled trial with follow-ups at 3, 6 and 12 months and assessments of treatment fidelity and the cost of SAFE’s delivery., Setting: The setting was (1) third-sector patient support groups and professional health-care organisations and (2) three NHS emergency departments in England., Participants: Participants were (1) people with epilepsy who had visited emergency departments in the prior 2 years, their significant others and emergency department, paramedic, general practice, commissioning, neurology and nursing representatives and (2) people with epilepsy aged ≥ 16 years who had been diagnosed for ≥ 1 year and who had made two or more emergency department visits in the prior 12 months, and one of their significant others. Emergency departments identified ostensibly eligible people with epilepsy from attendance records and patients confirmed their eligibility., Interventions: Participants in the pilot randomised controlled trial were randomly allocated 1 : 1 to SAFE plus treatment as usual or to treatment as usual only., Main Outcome Measures: Consent rate and availability of routine data on emergency department use at 12 months were the main outcome measures. Other measures of interest included eligibility rate, ease with which people with epilepsy could be identified and routine data secured, availability of self-reported emergency department data, self-reported emergency department data’s comparability with routine data, SAFE’s effect on emergency department use, and emergency department use in the treatment as usual arm, which could be used in sample size calculations., Results: (1) Nine health-care professionals and 23 service users provided feedback that generated an intervention considered to be NHS feasible and well positioned to achieve its purpose. (2) The consent rate was 12.5%, with 53 people with epilepsy and 38 significant others recruited. The eligibility rate was 10.6%. Identifying people with epilepsy from attendance records was resource intensive for emergency department staff. Those recruited felt more stigmatised because of epilepsy than the wider epilepsy population. Routine data on emergency department use at 12 months were secured for 94.1% of people with epilepsy, but the application process took 8.5 months. Self-reported emergency department data were available for 66.7% of people with epilepsy, and people with epilepsy self-reported more emergency department visits than were captured in routine data. Most participants (76.9%) randomised to SAFE received the intervention. The intervention was delivered with high fidelity. No related serious adverse events occurred. Emergency department use at 12 months was lower in the SAFE plus treatment as usual arm than in the treatment as usual only arm, but not significantly so. Calculations indicated that a definitive trial would need ≈ 674 people with epilepsy and ≈ 39 emergency department sites., Limitations: Contrary to patient statements on recruitment, routine data secured at the pilot trial’s end indicated that ≈ 40% may not have satisfied the inclusion criterion of two or more emergency department visits., Conclusions: An intervention was successfully developed, a pilot randomised controlled trial conducted and outcome data secured for most participants. The consent rate did not satisfy a predetermined ‘stop/go’ level of ≥ 20%. The time that emergency department staff needed to identify eligible people with epilepsy is unlikely to be replicable. A definitive trial is currently not feasible., Future Work: Research to more easily identify and recruit people from the target population is required., Trial Registration: Current Controlled Trials ISRCTN13871327., Funding: This project was funded by the National Institute for Health Research (NIHR) Health Services and Delivery Research programme and will be published in full in Health Services and Delivery Research ; Vol. 8, No. 39. See the NIHR Journals Library website for further project information., (Copyright © Queen’s Printer and Controller of HMSO 2020. This work was produced by Noble et al. under the terms of a commissioning contract issued by the Secretary of State for Health and Social Care. This issue may be freely reproduced for the purposes of private research and study and extracts (or indeed, the full report) may be included in professional journals provided that suitable acknowledgement is made and the reproduction is not associated with any form of advertising. Applications for commercial reproduction should be addressed to: NIHR Journals Library, National Institute for Health Research, Evaluation, Trials and Studies Coordinating Centre, Alpha House, University of Southampton Science Park, Southampton SO16 7NS, UK.)