This special issue reports the findings of the Mind and Spirit project. We ask whether different understandings of 'mind', broadly construed, might shape the ways that people attend to and interpret thoughts and other mental events -and whether their judgements affect their experience of (what they take to be) gods and spirits. We argue in this collection that there are indeed cultural differences in local theories of minds, in the way social worlds draws the line between interior and exterior, and that these differences do affect the way people sense invisible others. This introduction lays out the ideas that inspired the project and the methods that we used. This is the first report on our work.The Mind and Spirit project is a Templeton-funded, Stanford-based large comparative and interdisciplinary project under my direction, drawing on the expertise of anthropologists, psychologists, historians, and philosophers. The project asks whether different understandings of 'mind' , broadly construed, might be related to the ways that people experience what they take to be real. We looked specifically at gods and spirits because the evidence for invisible others often comes from anomalous thoughts and awarenesses, so that someone feels spoken to or senses a presence. If what counts as thought is different in different social worlds, so might the sense of what comes from outside.We took a mixed-method, multi-phase approach, combining participant observation; long-form semi-structured interviews; more structured epidemiological interviews in the general population about spiritual experience; large-scale surveys among local undergraduates; and psychological experiments with children and adults. Our fieldworkers were skilled ethnographers and researchers, competent in the local language, and experienced in local research. We worked in five different countries, which we chose because we took them to have different traditions in thinking about thinking: China, Ghana, Thailand, Vanuatu/Oceania, and the United States, with some work in the Ecuadorian Amazon. In each country, we included a focus on an urban charismatic evangelical church with additional work in a rural charismatic evangelical church, as well as another urban and rural religious setting of local importance. The team shared a conceptual framework, a common design, and a thematic focus. We held