The purpose of this study was to examine the psychometric properties of the Michigan School Libraries for the 21st Century Measurement Benchmarks (SL21). The instrument consists of 19 items with three subscales: Building the 21st Century Learning Environment Subscale, Teaching for 21st Century Learning Subscale, and Leading the Way to 21st Century Learning Subscale. The sample consisted of 54 respondents who were administered the instrument in 2014 and 2015. Cronbach's alpha for the total instrument was 0.807 (n = 19 items). Exploratory factor analysis (EFA) was used to measure construct validity. The findings derived from the EFA did not tend to support the original three-factor structure. The SL21 instrument is worthy of further study because of the dearth of literature that is focused on examining the psychometric properties of evaluation tools for school library programs. Perhaps a future study will use a revised survey instrument and a nationally representative sample. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]