The purpose of this quantitative, correlational study was to test Goddard et al.'s (2004) theory of collective efficacy by relating collective efficacy of both certified and noncertified staff to Missouri public high school students' ACT Scores. Additionally, it could be beneficial for future educational leaders to gain insight into collective noncertified staff efficacy and how that may relate to building culture, school size, and as a result, student achievement. As school culture continues to transform with each generation of students and staff, it is imperative school administrators understand the importance of cultivating a positive learning environment for employees and students. The researcher utilized Goddard et al.'s (2000a) Collective Efficacy Scale to survey Missouri public high school certified staff members. Furthermore, through a pilot study, the researcher utilized a pilot in order to create a revised version of Goddard et al.'s (2000a) Collective Efficacy Scale used for noncertified Missouri public high school staff. A principal component analysis was utilized in the pilot and the researcher used a multiple regression analysis after gathering data from both surveys. Data from the certified staff surveys showed statistical significance, however, the effect size was very small. Data from the noncertified staff surveys did not show statistical significance. [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.]