Nationally recognized social justice standards guide educators in developing social justice education. Absent from the guidance are tools to conduct initial formative assessment or to measure the impact of related instruction. To fill that gap, an academic researcher and 10th-grade teacher used a 3-phased, 9-step process to develop, pilot test, and evaluate a self-assessment tool called the Social Justice Educational Assessment Scale (SJEAS). In Phase 1, the team created the SJEAS items, aligning each with the Learning for Justice 9th-12th-grade social justice learning outcomes to ensure content validity. In Phase 2, they pretested the questions, revised the scale, and administered it to 322 student participants. Next, they conducted inter-item and total-item correlation tests and principal component analysis to ensure internal consistency. In Phase 3, they evaluated the SJEAS. Preliminary results indicate the SJEAS could provide educators and curriculum coordinators with a practical formative assessment and impact evaluation tool for social justice education aligned with nationally recognized learning outcomes. Complementary data, including classroom assignments and student discussions, would further enhance its value.