Health-system guidance (HSG) is expected to assist with making decisions about addressing problems or achieving goals in health systems. However, the implementation of HSG is challenging due to the complexity of health-system policymaking. Existing guideline implementation tools focus on clinical practice guidelines and might not be suitable for HSG. This dissertation aims to bridge this gap by developing a theoretical framework and a tool designed to support HSG implementation at both national and subnational levels. It achieves these objectives through three original scientific contributions. The first study uses a critical interpretive synthesis of the existing literature to develop a theoretical framework. This framework identifies facilitators of, barriers to, and strategies for supporting HSG implementation across six different levels: the political system, health system, community, organization, providers, and the public/patients. The second study employs a modified Delphi method to identify the components of an HSG implementation tool based on this framework. The third study adopts a formative evaluation study design to explore – through interviews with guideline implementers – whether, how, and why the HSG implementers will use the tool and how it can be refined, leading to the further development of the tool. These studies collectively offer theoretical, methodological and substantive insights into understanding the facilitators, barriers, and strategies crucial for the effective implementation of HSG. The developed HSG implementation framework and accompanying tool can be useful for supporting the implementation of HSG covering varied topics and in different contexts, including low-, middle- and high-income countries. / Thesis / Doctor of Philosophy (PhD) / Health-system guidance (HSG) is advice created to help governments make better decisions on how to improve health systems. The implementation of HSG is complicated due to the complex ways in which government policy about health systems is made. Most existing implementation tools are designed for implementing clinical practice guidelines, not HSG. This dissertation addresses this gap by focusing on HSG implementation, bringing together insights from a series of three studies. The first study develops a framework about the facilitators of, barriers to, and strategies for HSG implementation at different levels (e.g., patients, organizations and communities). The second study gathers expert opinions about how the framework can be used to develop the components of a tool. The third study examines whether, how, and why this tool will be used with people who implement HSG, which supports the further refinement of the tool.