Deep divisions persist within sociology over the potential of a neo-Darwinian selectionist paradigm of explanation to contribute positively to social theory and research. Herbert Spencer's concern with the progressive direction of evolution, and uncertainty about the divergences between Darwinian and Spencerian thought over ‘natural selection’ and the ‘survival of the fittest’, often freight preconceptions of the potential of the paradigm. This article first explains how ideas primarily attributable to Spencer rather than Darwin have served to cloud the debate. It thus clarifies Spencer's ideas on evolutionary process, disentangling them from and establishing their marginality to Darwin's central concerns. Second, it considers recent work by Runciman on selectionism and change in Britain, and suggests that the usefulness of adopting a selectionist paradigm need not (yet) involve a quasi-genetic unit of change as a component: novel ‘variations’, with some and not other practices ‘selected’ over time, may suffice. Third, it considers with examples, including Goffman on ‘stigma’ and the decline of the poor law, the new questions opened up for social theory by this modestly selectionist mode of analysis. It also discusses how recent work from neo-Darwinian, biologically-based researchers in the field of gene-culture coevolution is proving, in a complementary way, innovative in its conceptualisation of the central role of agency in social life.