The National Staff Development Council (NSDC), a private, nonprofit association, has outlined high standards for educator professional learning. One demonstration of NSDC's commitment to the goal of ensuring all schools support and use high standards for professional learning is the organization's investment in developing an instrument to assess the alignment of schools' professional development with NSDC standards. In 2003, SEDL developed The Standards Assessment Inventory (SAI) for NSDC, grounded in NSDC's standards which reflect the theoretical foundations and promising practices in school-based professional development literature. SEDL conducted three pilot studies to refine an initial bank of 100 survey items to 60 and began the process of establishing psychometric properties for the 12 standards represented by the instrument. The SAI was intended first to assess the quality of professional learning occurring at a school and to allow use of the findings to guide schools in improving professional development programs. The longer-term goal was to improve teachers' professional learning and thereby have a positive and sustaining effect on student learning. This research brief summarizes SEDL's research and development on the SAI to date, with specific emphasis on its psychometric properties, and presents the latest evidence on how teacher professional development contributes to student achievement. After providing background information on the development of the SAI, this brief presents the current findings on whether identifiable factors emerged from teachers' responses on the SAI, mapped onto the NSDC standards of professional development, and whether teacher assessment of professional development using the SAI was related to student learning. Measure Profile National Staff Development Council Standards Assessment Inventory (SAI) is appended. (Contains 4 footnotes.)