Teacher-librarians are awash in data. Studies on the impact of school library programs on student achievement have now been replicated in 12 states (more are in the works) with amazingly consistent results, these are added to studies dating from the early 1960s that support the importance of school library programs to student achievement and the importance of libraries and librarians in developing readers. Even the much-discussed "No Child Left Behind" legislation passed by the US Congress in 2001 has taken note of this research by including a section in the bill whose purpose is stated as follows: "... to improve literacy skills and academic achievement of students by providing them with access to up-to-date school library materials; technologically advanced school library media centers; and professionally certified school library media specialists" (NCLB, 2001). The author suggests that 3 responsibilities for teacher-librarians in regard to data about library programs are: (1) Know it; (2) Use it; and (3) Share it. She goes on to explain ways in which teacher librarians can challenge themselves to use data more skillfully to influence decision makers. Teacher-librarians need to adjust their thinking and learn to express program needs in terms of their potential to improve teaching and increase student achievement.