This article presents an original needs-based partial theory of human injustice and shows its relationship to existing theories of human need and human liberation. The theory is based on an original typology of three social structural sources of human injustice, a partial theorization of the mechanisms of human injustice, and a needs-based theorization of the nature of human injustice, as experienced by individuals. This article makes a sociological contribution to normative social theory by clarifying the relationship of human injustice to human needs, human rights, and human liberation. The theory contends that human injustice is produced when oppression, mechanistic dehumanization, and exploitation create systematic inequality in opportunities to address human needs, leading to wrongful need deprivation and the resulting serious harm. In one longer sentence, this needs-based theory of the sources, mechanisms, and nature of human injustice contends that three distinct social systemic sources—oppression, mechanistic dehumanization, and exploitation—produce unique and/or overlapping social mechanisms, which create systematic inequality in opportunities to address universal human needs in culturally specific ways, thus producing the nature of the human injustice theorized here: wrongfully unmet needs and serious harm.