Inclusion programs have expanded in schools across the country as educational leaders strive to meet the needs of a more diverse group of students. In response to Special Education legislation, schools and districts implemented programs and strategies for students with disabilities in the general education setting as increasing numbers of students with diverse needs were included. Inclusion reinforced the recognition that one person cannot effectively respond to the various psychological and educational needs of students in current classrooms. Many schools are now implementing the co-teaching model in response to the new demands on classroom teachers. By definition, the general education teacher and special education teacher work collaboratively to meet the individual needs of all students in an inclusive setting. Students with special needs, gifted students, English Language Learners, and all regular education students are held to the same standards on state developed assessments demonstrating accountability for teachers. It is critical that research-based instructional models are implemented in the classroom. School principals are responsible for monitoring and evaluating the instruction that takes place in the classroom to ensure research-based instructional practices are being implemented effectively. Since many schools or school districts chose to use the co-teaching model as a means of meeting the needs of all students and to ensure best practice, principals must have adequate knowledge of the model and be able to recognize effective implementation in the classroom. This study was designed to examine current practice in monitoring and evaluation of co-teachers and expert consensus regarding indicators of effective co-teachers in the inclusion classroom. This Delphi study utilized a mixed-methods research design. Three hundred five experts, selected from the 2012 Chicago Co-teacher training and current Arkansas co-teacher lists, were invited to participate in a two-round process. One hundred thirty-one responded in the first round to generate a list of indicators. Fifty-nine experts participated in the second round to rate the relevance of panel generated indicators and indicators from an existing instrument. Analysis of descriptive statistics revealed consensus for a majority of items from both sets of indicators. Though agreement was reached on all but one item as relevant, inter-rater correlation was low for all items. The study provided evidence for experts implementing the co-teaching model agreed upon specific indicators to help principals identify effective classroom practice. There was a lack of consistency and fidelity in using the specific indicators during program monitoring and teacher evaluation. [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.]