In September 2013 the Association of British Bookmakers (ABB) published a new voluntary code to promote responsible gambling. In February 2014 NatCen Social Research were commissioned by The Responsible Gambling Trust to evaluate the impact of the ABB Code (the Code). The first stage of the evaluation was to understand the underlying rationale or theory of the Code by mapping out the logic for the intervention, using a process known as a ‘logic model’. The aims of the logic model were for those responsible for designing and implementing the Code to articulate its intended outcomes, and the mechanisms by which these outcomes would be achieved. The logic model was developed collaboratively during two workshops with key stakeholders from the ABB and from the bookmakers’ industry. The logic model articulates the thoughts of those stakeholders about how the intervention will be implemented, what outcomes it will achieve and how these outcomes will come about.In the two workshops, it was agreed that the ultimate goals of the Code were to reduce gambling-related harm and to increase business responsibility and sustainability.To explain how these ultimate goals would be achieved, a series of short-, medium- and longer-term outcomes were articulated by participants across three broad areas: staff; machine tools; enhancements to existing practice.This report discusses each component of the logic model. It then sets out the perceived risks, challenges for measurement, and recommendations.