Review Paper Why is translating research into policy so hard? How theory can help public health researchers achieve impact? S. Gentry a,b,* , L. Milden a , M.P. Kelly a a Department of Public Health & Primary Care, Institute of Public Health, Forvie Site, Cambridge Biomedical Campus, Cambridge, CB2 0SR, UK b Norwich Medical School, University of East Anglia, Norwich, NR4 7TJ, UK article info Article history: Received 6 February 2019 Received in revised form 2 July 2019 Accepted 11 September 2019 Keywords: Public health policy Research impact abstract Objective: To describe how overly simple conceptualisations of how research is translated into public health policy impact impair effective translation. To suggest how alternative approaches to conceptualising impact, which incorporate recent developments in social and political sciences, can help stakeholders improve translation of high-quality public health research into policy impact. Study design: Researchers often describe generating impact in terms of linear or cyclical models, in which the production of scientific findings alone compels action and leads to impact. However, such conceptualisations do not appear to have supported improved translation of research into policy and practice. Improving understanding of how research impact is achieved may identify areas stakeholders seeking to achieve impact could target. Methods: Overview of theoretical and practical approaches to achieving public health policy impact from research. Results: Despite much evidence that translating research into public health policy is more complex than linear and cyclical models suggest, stakeholders often revert to these heu- ristics, that is shorthand ways of thinking that allow simple but inaccurate answers to complex problems. This leads to potentially missing opportunities for impact, such as conducting research in collaboration with local policy makers and contributing ideas to the wider narrative through the media and public engagement. Conclusion: The process of translating research into impact appears more complex than that suggested by linear and cyclical models. Success involves a planned approach tar- geting multiple routes to impact, sustained over time. © 2019 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved. * Corresponding author. Department of Public Health & Primary Care, Institute of Public Health, Forvie Site, Cambridge Biomedical Campus, Cambridge, CB2 0SR, UK. E-mail address: sarah.gentry@doctors.org.uk (S. Gentry). Available online at www.sciencedirect.com Public Health journal homepage: www.elsevier.com/puhe public health 178 (2020) 90 e96 https://doi.org/10.1016/j.puhe.2019.09.009 0033-3506/© 2019 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.