The growing focus on social and emotional learning (SEL) for children of primary grade age in conflict-affected and fragile contexts necessitates an understanding of the effects these programs have. However, the dearth of valid and reliable measures of SEL skills in low-resource and crisis contexts has constrained the generation of this evidence. The few tools that have robust psychometric properties were developed for use in high-resource contexts; they often have usage costs, limit adaptations, and focus on adults as respondents. To address this gap, we developed the International Social and Emotional Learning Assessment (ISELA), an adaptable, cost-free, open-source, performance-based measure of self-concept, stress management, perseverance, empathy, and conflict resolution in children between ages 6 and 12. In this study, we focused on establishing the validity and reliability of the ISELA when used with Syrian refugee children in Iraq. We tested the latent structure, criterion validity, internal consistency reliability, and interrater reliability of the ISELA with 620 Syrian children. We were able to establish a theoretically grounded factor structure for all of the skills except perseverance. The ISELA can be used reliably by groups of assessors (Krippendorf’s alpha>.86) with strong internal consistency (KR-20>.70). Our findings for criterion validity were promising but preliminary; grade and exposure to interpersonal threats demonstrated a positive association with SEL skills