Assessment literacy is an "individual's understanding of the fundamental assessment concepts and procedures deemed likely to influence educational decisions" (Popham, 2018, p. 2). The ability to make evidence-based decisions has become a non-negotiable skill for all educators. Unfortunately, most teachers do not have the skills or experience they need to be considered assessment literate. Determining how effective educators are at using assessments to make meaningful and productive instructional decisions is critical in planning and implementing professional development and training. This quantitative, comparative research study used the Teacher Data Use Survey to examine the four foundational supports for effective assessment literacy: Use of data, attitudes toward data, competency in using data, and the organizational supports for using data. The survey was sent to teachers and administrators to compare how the two groups responded. The purpose of this study was to determine how to best improve assessment literacy among teachers through effective and applicable professional development to maximize school improvement efforts. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]