Teachers have the responsibility to educate a diverse group of students in heterogeneous classes. One way in which teachers meet this challenge is to differentiate the curriculum to meet the needs, interests, and abilities of each student. One particular group of students in need of a differentiated curriculum to maximize learning potential is the gifted students. America's gifted students are not being given the chance to develop their talents to their fullest capabilities (Dixon et al. 2004). The problem that has surfaced throughout this study can be viewed through two different perspectives: concerns pertaining to teachers' ability to connect theory into practice and concerns pertaining to accountability. It is evident, due to the current era of accountability, that teachers are under pressure to raise test scores, resulting in a focus on underachieving students. The quality of general education and gifted curriculum is at risk due to primary concerns with minimal competency (Hockett, 2009). However, the GATE standards (2005) recommend that all gifted students receive a differentiated curriculum that focuses on depth, complexity of content, acceleration, and novelty. Therefore, the purpose of this study was to determine the type and degree to which teachers of the gifted differentiate curriculum in heterogeneous classrooms. This mixed methods study consisted of a survey followed by an observation of teachers who taught a gifted cluster of third through fifth grade students in a heterogeneous classroom. Various tests were conducted and the data analyzed to determine a relationship between what the teachers reported they used to differentiate for gifted students and what was actually observed taking place in the classroom. The results from the Spearman's Rho test found a correlation of -0.570, which indicated a negative relationship between what the teachers reported in the surveys and what was observed in their classrooms. This negative correlation maybe due to the challenge teachers face when applying theory they have learned in professional development training into practice. Educational researchers and professional developers need to understand the dilemmas and choices teachers have to make when applying what they have learned into practice (Battey, D. & Franke, M., 2008). Additional research is needed to support teachers of the gifted in the ability to bridge the theory to practice gap, resulting in an optimal learning environment for our most capable students. Gifted students have as much right to have their unique academic needs met as students anywhere else on the talent scale (Stanley, G., 2002). [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.]