In the period 1850-1875, Belfast experienced rapid urban growth, accelerating industrialisation and episodes of acute sectarian unrest. With a few short-lived exceptions, the town council remained under the control of a Tory cabal and a Protestant mercantile elite dominated the city’s associational culture. Keeping the civic politics of Belfast firmly in mind, this paper will explore the uneven political and cultural topography of the town’s scientific culture. Drawing on research conducted for the AHRC Scientific Metropolis project, it will first establish the scope of scientific activity undertaken in the town, establishing the wide range of civic societies involved in promoting science. Following this, it will turn to highlight a series of case studies or ‘moments’ which offer insights into the ways in which scientific discourse was put to work for political and religious ends. Two such case studies are provided by the meetings, hosted in Belfast in 1852 and 1874, of the British Association for the Advancement of Science (BAAS). The paper will discuss the planning for the 1852 meeting, reflecting on the political and religious makeup of the societies involved in its organisation, and will highlight an overlooked episode from the 1874 meeting – John Tyndall’s announcement of the end of the Belfast mill workers strike. In addition, the paper will investigate the short-lived history of the Belfast Working Classes Association, using it as a means to trace the emergence of a Catholic intelligentsia, and will highlighting the controversy surrounding the alleged anti-Catholicism of the guidebook prepared by the Belfast Naturalists’ Field Club for the 1874 visit of the BAAS. In addressing these episodes, the paper will seek to establish the complex nature of scientific associational culture in a divided urban context, and will complicate an existing narrative which portrays Belfast’s scientific societies as neutral spaces, unaffected by the town’s political and confessional realities.