ABSTRACT: Multimorbidity and its associated polypharmacy contribute to an increase in adverse drug events, hospitalizations, and healthcare spending. This study aimed to address: what exists regarding polypharmacy management in the European Union (EU); why programs were, or were not, developed; and, how identified initiatives were developed, implemented, and sustained.Change management principles (Kotter) and normalization process theory (NPT) informed data collection and analysis. Nine case studies were conducted in eight EU countries: Germany (Lower Saxony), Greece, Italy (Campania), Poland, Portugal, Spain (Catalonia), Sweden (Uppsala), and the United Kingdom (Northern Ireland and Scotland). The workflow included a review of country/region specific polypharmacy policies, key informant interviews with stakeholders involved in policy development and implementation and, focus groups of clinicians and managers. Data were analyzed using thematic analysis of individual cases and framework analysis across cases.Polypharmacy initiatives were identified in five regions (Catalonia, Lower Saxony, Northern Ireland, Scotland, and Uppsala) and included all care settings. There was agreement, even in cases without initiatives, that polypharmacy is a significant issue to address. Common themes regarding the development and implementation of polypharmacy management initiatives were: locally adapted solutions, organizational culture supporting innovation and teamwork, adequate workforce training, multidisciplinary teams, changes in workflow, redefinition of roles and responsibilities of professionals, policies and legislation supporting the initiative, and data management and information and communication systems to assist development and implementation. Depending on the setting, these were considered either facilitators or barriers to implementation.Within the studied EU countries, polypharmacy management was not widely addressed. These results highlight the importance of change management and theory-based implementation strategies, and provide examples of polypharmacy management initiatives that can assist managers and policymakers in developing new programs or scaling up existing ones, particularly in places currently lacking such initiatives.