Stress is a natural part of every adolescent's life. Adolescents in orphanage are more liable for stress than other adolescents. The aim of this study was to develop Orphanage Adolescents Stress Scale. Tool: The Orphanage Adolescents Stress Scale was developed by the researcher. Subjects and method: This questionnaire surveys were conducted with 74 adolescents to examine the psychometric properties. The final Orphanage Adolescents Stress Scale 58-items contain four domains: Emotional deprivation, Future planning, Relationships inside the organization, Relationships outside the organization and Stress symptoms. Result: Scale scores showed satisfactory internal consistency and two weeks test-retest reliability. Conclusion: OASS is an effective scale with acceptable psychometric properties and was especially adapted to measure stress in orphanage adolescents. Recommendations: For researchers who have a particular interest in stress among orphan adolescents, the OASS suggested to be effective tool.