Using data from national surveys of teachers and school districts, this brief provides the first national estimates of the prevalence of K-12 teachers' access to and use of electronic student data management systems. Specifically, the brief seeks to determine how broadly student data systems are being implemented in districts and schools; the prevalence of tools for generating and acting on data are within these systems; and how school staff are using student data systems. Nearly half of all teachers reported having access to an electronic student data management system in school year 2004-05, and a majority of those teachers reported making use of it for monitoring student progress, planning, and refining their instruction, or keeping parents informed. This paper was developed through a secondary analysis of national survey data from over 6000 teachers and over 1000 district technology coordinators conducted in 2005 as part of the National Educational Technology Trends Study. (Contains 9 exhibits and 6 footnotes.)