While there is an abundance of philosophical literature on justice, there is far less literature within political philosophy on the topic of injustice. I think one common assumption these approaches share is that injustice is simply the absence of justice; call this the absence thesis. This assumption becomes more peculiar juxtaposed to social and political struggle for justice, which quite commonly begins with cries of injustice. Injustice is an importantly distinct philosophical notion from justice – it can explain how justice fails to be realized in interesting and sophisticated ways, and, I argue, track our efforts to realize just social worlds, in ways that paradigmatically ideal and nonideal approaches to justice by themselves cannot. In this essay, I focus specifically on the question of how theories of justice can guide action in social worlds with systematic oppression. I ultimately argue that action-guiding theories of justice that evaluate worlds with systematic oppression must represent features of injustice. If a theory fails to represent features of injustice, it will fail to guide action in these worlds. That representation of such features is necessary gives us reason to think, in certain circumstances, that the absence thesis is false.