The purpose of this project was to define the current state-of-the-art in the detection and attribution of human health impacts of human-caused climate change, sometimes shortened as health impact attribution. As this interdisciplinary field of research has emerged over the last decade, the numbers of deaths from extreme heat, storms, floods, many climate-sensitive infectious diseases, and some other climate change-related risks has increased markedly. Health impact attribution has the potential to bring to light these growing costs of climate inaction—but only if the field can catch up to the rapidly-evolving crisis. This report provides an overview of the field as it stands today, including reflections on the history of its evolution out of climate science; an overview of the aims and approaches of the current body of literature; a deep dive on the data and tools that have been applied to the problem so far; and suggestions on how the field could progress in the future. Throughout, we reflect on four key areas—data, tools, talent, and policy—at the heart of the Wellcome Trust’s strategy on data science for climate change and health, and we highlight opportunities in each of these areas that could help advance health impact attribution.