Diversity in schools is at an all-time high, and student diversity will continue to increase (Crouch, 2012; Tomlinson, Brighton, Hertberg, Callahan, Moon, Brimijoin, Conover, & Reynolds, 2003). The result is a need for teachers to respond to the differences among students. Teachers can respond to student differences through differentiated instruction, maximizing students' potential by honoring their learning needs (Santangelo & Tomlinson, 2012). Most teachers are familiar with differentiated instruction, but many teachers do not differentiate their instruction on a regular basis. Research has determined the factors predicting implementation of differentiated instruction. It is unclear which of the factors is the strongest predictor of implementation. This quantitative study sought to determine the strongest factor predicting implementation of differentiated instruction. Participants are K-8 teachers in two large suburban school districts in southern New Hampshire. Results determined that perception is the strongest predictor of implementation of differentiated instruction. [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.]