This paper examines the role of ethnicity in the Sri Lankan governments of the United Front (1970-77) and the People's Alliance (1994-2001). In particular, it examines the way in which the category of ethnicity was redeployed by Left theorists associated with these specific regimes. The paper looks at several key texts of each period in order to identify the major positions. It finds that whereas in the United Front ethnicity was reduced to class, in the People's Alliance ethnicity was operationalized as an autonomous variable of research and policy. These two contrasting positions were implicated with shifts in the wider political economy of Sri Lanka.