This essay examines the tensions between participatory ethnographic research methods and newly emerging legal regimes of data protection and privacy. Drawing on the example of recent grant-funded research in Mexico, the essay charts how the European Union's General Data Protection Regulation impedes the practices and ethos of participatory research in significant ways. In particular, new legal requirements about data collection, access and storage, and "the right to be forgotten," effectively preclude integrating community members into research planning or data collection. As countries around the world move toward more robust and comprehensive data protection and privacy laws, the issues raised in this essay are likely to become more pressing in many different research contexts in the future. [Mexico, data protection, participatory research, privacy laws]. I n t r o d u c t i o n S ince at least the 1990s, developing participatory research methods have offered anthropologists an avenue through which the power hierarchies inherent in traditional ethnographic research may be destabilized. As many of the contributors to this collection show, by inviting research participants to take an active role in the development of research questions, activities and outcomes, participatory research has enabled anthropology to expand its practice, both conceptually and ethically. In addition to these disciplinary achievements, participatory research also aims to enable marginalized people to transform the conditions of their lives and communities by giving them research skills that they can use to work toward their own goals (Park 1993; Hurtig 2008). As Little and Rees (this issue) suggest in the introduction, participatory research is not only a methodology, it is also a political stance that seeks to place community members on equal footing with the researcher and their institution's interests and agendas. On the ground, participatory research spans a spectrum of practices. These may be primarily community-focused, such as formal skill-building at local levels through workshops and training sessions (Batallan, Dente, and Ritta 2017). Researchers may also make themselves useful to the people with whom they work by contributing their time and expertise to community-led projects during the research period (Taylor this issue; see Simmons 2010). Other practices are more concerned with bringing participants into the research process itself. This may include involving participants in the development of research questions and data-collecting activities, including interviews and