The extent to which government should partner with business interests such as the alcohol, food, and other industries in order to improve public health is a subject of ongoing debate. A common approach involves developing voluntary agreements with industry or allowing them to self-regulate. In England, the most recent example of this was the Public Health Responsibility Deal (RD), a public–private partnership launched in 2011 under the then Conservative-led coalition government. The RD was organised around a series of voluntary agreements that aim to bring together government, academic experts, and commercial, public sector and voluntary organisations to commit to pledges to undertake actions of public health benefit. This paper brings together the main findings and implications of the evaluation of the RD using a systems approach. We analysed the functioning of the RD exploring the causal pathways involved and how they helped or hindered the RD; the structures and processes; feedback loops and how they might have constrained or potentiated the effects of the RD; and how resilient the wider systems were to change (i.e., the alcohol, food, and other systems interacted with). Both the production and uptake of pledges by RD partners were largely driven by the interests of partners themselves, enabling these wider systems to resist change. This analysis demonstrates how and why the RD did not meet its objectives. The findings have lessons for the development of effective alcohol, food and other policies, for defining the role of unhealthy commodity industries, and for understanding the limits of industry self-regulation as a public health measure.