This research brief reports on findings from an on-line survey conducted by the American Institutes for Research (AIR) to study state education agency capacity to develop and deploy a statewide system of support for schools identified for improvement under No Child Left Behind (NCLB). To provide support commensurate with the challenges facing low-performing schools, state education agencies need adequate capacity--including infrastructure, professional resources, and political support. Data from a survey of state officials in all 50 states reveal that: (1) State officials report limited capacity to support school improvement: only 16 states reported "moderate" capacity while 33 reported limited capacity; (2) Respondents in states with more challenging workloads perceived lower levels of capacity; and (3) State officials generally perceive expertise within the state education agency to be a strength, although they report lower levels of expertise regarding the needs of English language learners. In summary, state officials perceive constraints associated with their own capacity to provide support to low-performing schools, particularly with regard to staff, funding, and technology. This brief is a companion to "State Systems of Support under NCLB: Design Components and Quality Considerations" (ED502718). (Contains 4 exhibits and 18 endnotes.)