Recently, there has been an increasing awareness of the global threat to human and animal health that is presented by the failure of germs, specifically bacteria, to respond to treatment with medicines which formerly killed them, a phenomenon known as Antimicrobial Resistance (AMR). Many approaches are being explored to ameliorate this problem, including the critical need to make better use of antibiotics. Optimal use of antibiotics must ensure both that people unwell with bacterial infections continue to have access to medicines that they need and bacteria do not have the opportunity to develop resistance to these "magic bullets". Huge investments have been made in improved laboratory capacity, which permits us to detect and describe AMR and report this problem through surveillance networks to governments and international agencies. These investments in laboratory surveillance have not been matched by enhanced surveillance of or interventions to improve antibiotic use (ABU), particularly in low income countries. We propose to bring together four Global Challenges Research Fund (GCRF) investments in the field of AMR in East Africa into a GCRF cluster. We will collectively take responsibility for reviewing and "synthesising" all of our ABU research findings from the East African context from across human and animal health. We will work together to co-design "an essential information package" to optimise ABU in the East African context and to define an intervention using this package to change ABU behaviours in communities and health systems. EPSRC Grant No EP/T024984/1 Liverpool School of Tropical Medicine, United Kingdom University of Glasgow, United Kingdom University of St Andrews, United Kingdom The University of Sydney, Australia University College London, United Kingdom Infectious Diseases Research Collaboration, Uganda London School of Hygiene & Tropical Medicine, United Kingdom African Institute for Development Policy