The long arc of Marxist scholarship certainly reaches many domains—economics, sociology, political ecology. However, few scholarly projects have likely benefited more, or offered more, to sustaining the relevance of Marx and Marxism than the feminist analysis, interpretation, and application of the Marxist critique of capitalism. From the earliest translations of Marxist thought into revolutionary action, socialist feminists have sought to introduce sex and gender as salient categories of capitalist oppression, arguing that being a woman bound to patriarchal institutions such as marriage is comparable to a working-class laborer bound to the wage. Friedrich Engels also plays a key role in the socialist feminist appropriation of Marxist ideas. By showing the extent to which marriage is about the maintenance and expansion of property, Engels opens the door to a wide range of analysis concerning the material conditions of women’s lives and labors. Marxist ideas become the focus of renewed interest over the course of the American civil rights and feminist movements of the 1960s. It is thus unsurprising that a wealth of new feminist and antiracist theories begin to develop during this period, as well as analyses of structural inequality, including oppression with respect to the LGBTQ community. It is perhaps the most recent work among socialist feminists, in league with other activists and theorists, however, that is both truest to Marx’s original intent and that demonstrates the relevance of his ideas to the future fortunes of human societies, namely, the application of Marxist critique to environmental deterioration—especially anthropogenic climate change. Hence, the following is organized historically but also topically. It begins with the work of early socialist feminists, looking to include women within Marxist categories of class analysis but quickly moves to arguments that sex and gender—and then race/ethnicity and sexual identity—constitute their own salient categories of oppression. This explosion of theory and activism deserves to be treated topically so that the variety and breadth of socialist feminist ideas as well as the divisions and debates among its representatives becomes clear. The critique of capitalism has, of course, always been an essentially global enterprise. It is thus not surprising that the extension of socialist feminist analyses to the Global North and Global South would produce a wealth of insight and activism. For many of the same reasons, the same is true of the rise of socialist ecofeminism. The last section comes full circle. Devoted to arguments whose focus is the justification and fomenting of revolution, The Communist Manifesto finds its place next to contemporary socialist ecofeminist calls for workers from all regions of the planet to unite to overthrow once and for all the capitalist economic system responsible for jeopardizing the planet’s capacity to support life.