Introduction and Aims: The structures of health systems impact on patient outcomes. We present and analyse the first detailed mapping of who funds alcohol and other drug (AOD) treatment and the channels and intermediaries through which funding flows from the funding sources to treatment providers.Design and Methods: The study involved a literature review of AOD treatment financing and existing diagrammatic representations of the structure of the Australian health system. We interviewed 190 key informants to particularise the AOD treatment sector, and undertook two case examples of government funded non-government organisations providing AOD treatment.Results: Funding sources include the Australian and state and territory governments, philanthropy, fund-raising and clients themselves. While funding sources align with the health sector generally and the broader social services sector, the complexity of flows from source to treatment service and the number of intermediaries are noteworthy. So too are the many sources of funding drawn on by some treatment providers. Diversification is both beneficial and disadvantageous for non-government treatment providers, adding to administrative workloads, but smoothing the risk of funding shortfalls. Government funders benefit from sharing risk.Discussion and Conclusions: Circuitous funding flows multiply the funding sources drawn on by services and put distance between the funding source and the service provider. This leads to concerns over lack of transparency about what is being purchased and challenges for the multiply funded service provider in maintaining programs and service models amid multiple and sometimes competing funding and accountability frameworks. [Chalmers J, Ritter A, Berends L, Lancaster K. Following the money: Mapping the sources and funding flows of alcohol and other drug treatment in Australia. Drug Alcohol Rev 2016;35:255-262]. [ABSTRACT FROM AUTHOR]