Horizontal coordination mechanisms can take different shapes in practice: they can range from being task specific and of short duration to deal with an urgent policy problem to forums with encompassing policy scope, permanent staff, formalised meetings, and regular interactions. Based on the chapters in this book, we find several shared characteristics of horizontal coordination mechanisms across countries, such as local government associations for interest representation and information sharing on all areas that fall into the jurisdictions of local governments, or a wealth of coordination activities for regional economic development and investment at the meso-level (supra-local, sub-regional, or regional) to match the scale of complex policy problems and respond to the consequences of urbanisation and regional inequalities. Among the facilitators of coordination, political will, shared knowledge and funding matter for starting a coordination initiative as well as for producing tangible outcomes. Clarity of responsibilities and a high degree of decentralised authority are furthermore beneficial, as they provide political actors with the opportunity to act and engage in coordination processes. Among the barriers to effective coordination are a lack of resources, unfavourable macroeconomic conditions, as well as territorial inequalities. Political contexts and variations in the political composition of governments, in comparison, matter more for vertical coordination mechanisms but seem to be less important in the case of horizontal coordination unless they coincide with ethnic conflicts further dividing the population and political elites.