The Positive Behavior Interventions and Supports (PBIS) framework is a research-based model that yields positive behavioral, social, emotional, and academic outcomes (Horner et al., 2009; Horner, 2014; Mathews et al., 2013). However, schools have reported varied success rates with implementation and achieving desired outcomes. While hundreds of studies have been conducted on PBIS implementation, few have focused on small, rural school populations. This mixed methods study used linear regression analysis to investigate the relationships between PBIS implementation levels, teacher efficacy, and professional development. It involved data from an administrator screener, multiple teacher surveys, and interviews with teachers and administrators from small, rural schools in Ohio. The independent variable examined was teacher efficacy and the dependent variables include quantity of training and type of training. Qualitative data from two administrator and two teacher interviews was used to gain insight into the challenges and obstacles that interfere with PBIS implementation. Their responses were recorded and transcribed using Zoom Meeting platform. Deductive and inductive coding processes were applied to identify facilitating and impeding factors. Results revealed no significant relationship between teacher efficacy levels and the type of training schools provided. However, a positive relationship was found between the quantity of training received and teachers' collective efficacy scores. These findings yielded a predictive model showing that collective efficacy scores increase about one point on a 9-point Likert scale for every 4-5 hours of training. In addition, qualitative results confirmed the previous research that identified administrative support, ongoing coaching and training, and positive teacher belief/staff "buy-in" as facilitating factors in PBIS implementation. Furthermore, the study found that a grassroots effort over legislative demands, staff collaboration, and consolidation of PBIS implementation with MTSS duties were specifically helpful for PBIS implementation in small, rural schools. [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.]