The sociolinguistic enterprise raises fundamental questions about the nature of the relationships between social phenomena (such as social class or gender) and linguistic variation, while within social theory a persistent concern is the nature of the relationship between structure and agency. Sociolinguistics can draw on social theory for analysis of the relationship between speaker and system, the role of language in the creation, maintenance and change of social institutions, and the role of human agency in sociolinguistic phenomena. This article summarises the key tenets of a sociological realism, based on the recent work of Margaret Archer (in particular her exploration of analytical dualism) and of Derek Layder (specifically his theory of ‘social domains’). It relates these ideas to sociolinguistics, arguing that language can be seen to have a different significance, depending on which domain is the focus of the researcher's interest. The article considers the distinctiveness of this approach, contrasting it with structuralist and social constructionist accounts and with structuration. It concludes by identifying some methodological implications, suggesting that sociological realism offers a productive theoretical framework for sociolinguistics in dealing with questions of language, structure and agency.