Abstract: This article argues that Indigenous people were visible and agential participants in the American Left long before the explosion of Native activism in the 1970s. By situating Indigenous people in the interwar Communist Party, the article makes two major contributions to the histories of Indigeneity and socialism in twentieth-century USA. First, the article argues for a history of the Popular Front that is thoroughly attuned to the complex ways that settler-colonialism structures Left politics in the Americas. The interwar Left produced genuinely radical critiques of the USA as a colonial project and demonstrated a real appreciation of the US’s origins in the genocidal violence of European capitalism. But it failed to undertake a Marxist theorisation of Native oppression, leading to programmatic absences, problematic representations and persistent theoretical ambiguities. This mixed legacy helped set the stage for extensive debates later in the century about the compatibility between Marxism and Indigenous struggles for land sovereignty and cultural autonomy. Second, the article situates late-twentieth-century Native radicalism within a longer history of Indigenous affiliation with the organised Left, demonstrating how effective such alliances could be, even as non-Native communists betrayed their ignorance of Native culture and proved somewhat inconsistent in their ideas about Native sovereignty. The article invites more thoroughgoing assessments of the various and complex ways that the US’s settler-colonial character has historically structured – and been challenged by – the militant Left.