This section of the book provides key examples in which policy sectors appear to have their own policy styles. This introductory chapter provides a broad framework in which to understand potential sectoral differences. It begins with a discussion of the broad context, in which I highlight the general logic of distinctive sectoral policy styles and the rationale for organising policymaking along sectoral lines. A focus on sectors allows us to identify the same issues and ask the same questions that we apply to national and international comparisons. First, from where does the story of policy communities, in sectors or subsectors, begin? Second, can we use the same collection of policy concepts to set up a broad framework to understand sectoral comparisons? Third, how do we identify the boundaries between each sector? Fourth, can we apply the same policy theories to each sector, or do some theories travel more or less well across sectors? Finally, this chapter explores the extent to which sectoral styles undermine intersectoral action.