The first and oldest of the British missionary societies was the Society for the Propagation of the Gospel (SPG). It has a major historiography, which now extends over its full 300-year history to cover the entire period of the rise and fall of the British empire. This chapter examines the way in which the Society moulded its original Charter in the nineteenth century to meet the changing tides of religious and imperial policy. It concentrates on two periods of reform when the SPG was forced to redefine its role and the mission to British settlers that earlier had been its most characteristic work. The first was in the 1840s when the launch of the Colonial Bishoprics' Fund (1841) sparked renewed enthusiasm for Anglican expansion into the settler colonies. The second occurred at the end of the century under the leadership of Henry Hutchinson Montgomery (1847–1932), formerly bishop of Tasmania, and Secretary of the SPG from 1901 to 1918. As Secretary of the SPG in the heyday of British imperial power, Montgomery was responsible more than anyone for articulating a coherent ideology for the Anglican missionary movement that attempted to unite Christian idealism with British imperial nationalism. That he failed to win majority support within the British Anglican communion for this vision suggests that, even at the height of the imperial age, colonial missions enjoyed only limited appeal.