Corporations are increasingly asked to specify a ‘purpose.’ Instead of focusing on profits, a company should adopt a substantive purpose for the good of society. This chapter analyses, historicises, and radicalises this call for purpose. It schematises the history of the corporation into two main purpose/power regimes, each combining a way of thinking about corporate purpose with specific institutions to hold corporate power to account. Under the special charter regime of the seventeenth to mid-nineteenth centuries, governments chartered companies to pursue specific public purposes. Under criticism for corruption and lack of competition, the special charter regime gave way to the contemporary general incorporation regime, under which no particular purposes are demanded of corporations, and profit-seeking has become the norm. This regime has now come under criticism, with calls for a new social purpose regime. The analysis of these three regimes focuses on politicisation. The chapter argues that orienting companies to substantive social purposes requires politicising the business corporation, creating meaningful accountability mechanisms to align companies with the goals of the public. The purpose paradigm must overcome its political timorousness and be more institutionally radical. The difficulty is doing this without unacceptable corruption and inefficiency. A form of ‘proper politicisation’ is needed. At the end of the chapter, some directions for reform are discussed, which may deliver on that desideratum.