This study describes the development of a 12-item inventory of school supports for military-connected (MC) children. Participants were 444 students (grades 3 or 5) with an active-duty military parent (48% female; 57.3% White, 10.7% Black, 6.2% Native American, 5% Asian, 3.3% Pacific Islander, 17.5% bi/multiracial; 19% Latinx). Youth completed the Inventory of School Supports--Youth Report (ISS-YR) and measures of academic efficacy, parental involvement in school, school connectedness, and whether they had a non-parental supportive adult in their life. Parents reported on parent-teacher relationship quality. Confirmatory factor analyses supported a two-factor model (functional and relational support). Results psychometrically supported the ISS-YR. Scores demonstrated adequate internal consistency reliability. Results also supported the measure's convergent and criterion validity as evidenced by positive associations with school connectedness, academic efficacy, parental school involvement, and parent-teacher relationship quality. Youth with a supportive adult in their life at and outside of school had the highest ISS-YR scores. Implications of these findings for schools' efforts to support MC students are discussed.