Within the field of peace education and related areas, there is a general consensus about the nature of peace and although there are numerous references and mentions of justice, there are no clear descriptions or systematic study of what justice is, in relation to peace. Among peace educators, Betty Reardon's numerous writings articulate, implicitly, a coherent theory of justice. Reardon's approach to peace education inquires into the nature of peace. Reardon asks what peace is, and the question that follows is, “What comprises peace?” From Reardon's perspective, justice is required for peace. As found in the literature, Reardon's peace education writing illustrates consistency and similarity with capabilities. Reardon's perspective of justice, I would assert, is a capabilities approach. Capabilities are a species of human rights that represent substantive opportunities and freedoms that allows individuals to do and be as they choose (and required by human dignity). Reardon’s conception of justice is similar to the prominent capabilities perspectives of Nobel laureate Amartya Sen and University of Chicago philosopher Martha Nussbaum. A clear understanding of what justice is, in relation to peace and peace education, is a useful tool for learning, scholarship and practice. Knowing what justice is informs peace.