Following experimentation beginning in the mid 1990s, the Thames Valley Police initiated a formal program of restorative cautioning in the spring of 1998. It was the first step in a larger program of restorative-oriented change within the Thames Valley Police. In this context, the restorative cautioning initiative has proven to be the most significant development to date. Hence, the Thames Valley Police’s restorative cautioning was the subject of a three-year research project – an action-research project in that the researchers were committed to assisting the police to improve their practices. The researchers collected qualitative and quantitative data through observing and tape-recording restorative processes, and also through interviews with all the participants. In this chapter, Young and Hoyle present certain findings from that research. The chapter covers the significance and scale of the Thames Valley Police initiative; the reasons from an action-research strategy; and findings on the quality and outcomes of this particular restorative justice process. The research findings, focused on the actual process of restorative justice as delivered within a policing context, illuminate the developing practice of police-led restorative justice in the United Kingdom.