Mission statements are expected elements of business plans and corporate communications. Yet, practice in creating them and monitoring their impact varies and skeptics wonder about their usefulness. A survey of business literature provides a context for school library mission statements. Mission statements define the nature, purpose, and role of organizations; focus resources; and guide planning. Mission statements in K-12 education reflect community priorities and typically include themes of cognitive, social, and civic development. The effect of mission statements on performance is unclear, but some suggest that the degree of commitment to shared purpose distinguishes high-performing schools from failing schools. This article describes the role mission statements play in school libraries.