Understanding the Impact of Innovations in the Regulation of Kenya's health facilities Health systems in low and middle income countries (LMIC) are increasingly pluralistic, involving a wide mix of public, not-for-profit and for-profit providers. Regulation should be a key foundation of the Government's stewardship role of these heterogeneous facilities, but performance of this function is generally weak, with serious consequence for patient safety and quality of care.   There has been little evaluation of strategies to strengthen regulation in LMIC, a notable exception being the Kenya Patient Safety Impact Evaluation (KePSIE), a collaboration between the Kenyan Ministry of Health and the World Bank. This randomised controlled trial is assessing the impact of a set of innovative regulatory interventions in public and private facilities in 3 Kenyan counties. These comprise the use of the Joint Health Inspections Checklist (JHIC), which synthesises the areas covered by all the regulatory Boards and Councils; increased inspection frequency; risk-based inspections where warnings, sanctions and time to re-inspection depend on inspection scores; and display of regulatory results outside facilities.  The KePSIE trial will provide a rigorous quantitative assessment of these regulatory strategies. However, such regulatory interventions are highly complex, requiring behaviour change by regulatory managers, front line inspection staff, health facilities, and clients. To understand the effectiveness of the intervention and why aspects do (or do not) work it is therefore essential to investigate the mechanisms and processes involved, the degree to which they are implemented effectively, and the reasons for the level of implementation observed. Other important dimensions include legitimacy, potential for corruption and regulatory costs. We will therefore conduct a companion study to enhance our understanding of the effectiveness of these regulatory innovations, and to consider their wider implications for the creation of a cost-effective, sustainable and equitable regulatory system.  The research will begin with a review of key documents and records related to regulatory implementation, with the review updated periodically during the study. We will also systematically collate media articles from Kenyan newspapers and relevant social media concerning health facility regulation. Following a period of familiarisation with regulation by shadowing inspectors on their regular duties, we will undertake a set of in-depth interviews (IDIs) with a wide range of stakeholders including national regulators, county and sub-county managers, inspectors, facility owners/ staff, and Community Health Committee members. IDIs will cover their perceptions and experiences of regulatory implementation under the current regulatory system and the KePSIE regulatory innovations; their views on the legitimacy of regulatory systems, in terms of fairness and acceptability; perceptions of corruption; and perceptions of community views on facility regulation. We will also conduct patient exit interviews to assess community member understanding of the regulatory scores displayed outside facilities. Finally, we will assess the incremental costs of the KePSIE interventions compared to those of the current regulatory system, from the perspectives of both the regulating agencies and the health facilities.  The results are expected to make an important contribution to the limited evidence base on regulation and regulatory reform. The findings will be of substantial benefit to those concerned with regulatory reform and the improvement of quality and safety more generally in Kenya and other LMIC settings. The Global Challenges Research Fund (GCRF) supports cutting-edge research to address challenges faced by developing countries. The fund addresses the UN sustainable development goals. It aims to maximise the impact of research and innovation to improve lives and opportunity in the developing world.