This chapter sets out theories of state-building, connecting the themes of the book around the Board of Trade to the context of British state-building. It puts forward five types of state that the British state went through: the mercantile state; the fiscal-military state; the imperial-corporate state; the slave state; and the regulatory state. These were overlapping types of state with a rough chronology, but with interconnections and interactions between them. It unpacks the ways in which the British state was based around mercantile interests, and the leading theories of the fiscal-military state. It builds on these theories to include more recent work on the building of empire through corporations and integrating slavery and the slave trade into the story of British state-building. The thread of building the British regulatory state runs through the three centuries covered by our book, building on medieval labour and guild regulation of prices, wages, occupations, and poor laws, through to regulation of companies and infrastructure that the Board came to create and administer. Its argument is that regulation of labour was always stricter and more rigid than regulation of certain sorts of capital; in particular that regulation of financial and commercial capital with international trading links was less stringent than regulation of industrial capital.