The CASE PhD studentship project will develop a measurement system for evaluating return on investment (ROI) of quality improvement projects in mental health services of the South London and Maudsley (SLaM) NHS Foundation Trust. Quality improvement in healthcare has seen a surge of investment amidst times of austerity in the UK. Very little guidance exists for evaluating return on investment, particularly in mental health NHS Foundation Trusts. This impedes communication with healthcare leaders and boards regarding the extent quality improvement is achieving its full potential within the organisation. A robust ROI measure will make it possible to generate regular reports for healthcare leaders. These routine reports can provide a big picture to give healthcare leaders strategic insights about the extent resource commitments in quality improvement paid off. On this basis, decisions can be made about investment strategies for capacity building and training. We would also be able to compare NHS Foundation Trusts in terms of ROI of their organisational strategies and quality priorities. By generating insights on ROI, the routine use of this measure can also foster a culture of organisational learning that is pivotal for a learning healthcare system. The research will involve integrating knowledge and methods from psychometrics, health economics, and the interdisciplinary social science fields of implementation and improvement sciences. The first priority is to clarify the concept of ROI so that we have an appropriate basis to generate insights for healthcare leaders. The links between ROI and Value Based Healthcare will be of particular interest. Across King’s Health Partners, Value Based Healthcare is established as a key approach to achieve better outcomes and experiences for every person with the equitable, sustainable and transparent use of the available 3 / 12 resources. We will explore these links in the research literature as well as through individual/group interviews with the executive leadership team (e.g., Chief Medical / Financial / Operating Officer) as well as the senior management team (e.g., Clinical / Service Directors). Based on these initial insights, we will develop field-test version of a ROI measure through group consultation in various stages. The groups comprise both the executive leadership and senior management teams who will review content validity and item design, as well as debate on implementation issues like acceptability, reach, and sustainability of routine ROI reports. The newly developed ROI measure will be field-tested with data from three psychiatric hospitals of SLaM (Bethlem Royal Hospital, Lambeth Hospital and the Maudsley Hospital). The validation study will refine the field-test version and derive a final version that can be embedded in routine evaluation to inform organisational decision making on quality improvement investments.