This study examines teacher efficacy within the context of professional development to understand the relationship between teacher efficacy and teacher collaboration. Two theoretical frameworks framed this teacher efficacy study based on "locus of control" and "social cognitive theory." A 29-item questionnaire was e-mailed to approximately 500 K-5 classroom teachers, special education teachers, and Title I specialists in 18 elementary schools and two K-8 schools in a suburban school district where the practitioners participated in staff development on the language arts and math adoption using the district-developed response-to-intervention model, Instructional Intervention and Progress Monitoring. Descriptive statistics, correlations, cross-tabulation and chi-square analyses were used to investigate the relationship between the level of teachers' participation in the professional development and their sense of efficacy. [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.]