This study investigated the construction and evaluation of an instrument called the Perceptions of Success Inventory for Beginning Teachers (PSI-BT) intended to measure factors documented in research that contribute to beginning teachers' perceptions of success. The PSI-BT was found to assess the following factors using exploratory factor analysis: (1) Administrative Support, (2) Classroom Climate, (3) Mentor Support, (4) Colleague and Instructional Resource Support, (5) Commitment, and (6) Assignment and Workload. Internal reliability, content validity, and concurrent validity were also measured in the validation process. Our findings suggest that the PSI-BT provides a reliable and valid instrument that can provide schools with valuable feedback to ensure the success of their beginning teachers. (Contains 4 tables.)