Differentiated Instruction is an approach to teaching which meets the diverse academic needs of students by considering learner readiness, interest and learning style. The approach is grounded in the socio-cultural, multiple intelligence and learning style theories. In addition, differentiation is a research based method for meeting the expectations of No Child Left Behind to raise the achievement of all students. Although current literature describes how to best implement differentiated instruction, there is a lack of research describing teacher perceptions on implementing the approach (Subban, 2006; Hall, Strangman, & Meyer, 2003). Thus, it is helpful to examine how teachers understand and perceive the influence of differentiation on instructional practices. The present study utilized the qualitative method of phenomenology to explore teacher perceptions connected to differentiated instruction and the influence of these on instructional practice. The study interviewed 11 intermediate elementary school teachers using interview questions to promote conversational dialogue. The interview questions afforded teachers opportunities to share their thoughts, feelings, and experiences pertaining to differentiated instruction. Data analysis revealed the following themes: 1) Differentiated instruction is essential in an effective classroom, 2) differentiated instruction occurs naturally, 3) in-service professional development influences differentiated instruction, 4) early schooling influences differentiated instruction, 5) pre-service professional development influences differentiated instruction, 6) differentiated instruction is prevalent and 7) classroom environment conducive to learning. In addition the study found that teachers used the following differentiated instructional strategies: flexible grouping, tiered lessons, literature circles, and curriculum compacting. Consequently, this study supports differentiated instruction as an approach to learning while highlighting the influence of professional development on teachers' use 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/en-US/products/dissertations/individuals.shtml.]