Teachers need practices that can be implemented in the classroom to teach children how to address conflict and solve problems proactively. There are curricula available for teachers to use in promoting improvement in the social behavior of students and for further enhancing their ability to self-regulate their behavior (Smith, Lochman, & Daunic, 2005). The focus of this study was two-fold. One focus was to identify teachers' concerns regarding the implementation of a social problem-solving curriculum for fourth and fifth grade students. The second focus was to examine how teachers who have been trained to implement a promising practice continue to use that practice over time. The present investigation used a mixed-method design using the Concerns-Based Adoption Model framework (Hall & Hord, 2006) to examine how teachers' concerns contribute to or impede the adoption and sustainability of an intervention. The Stages of Concern Questionnaire was used to identify teachers' concerns with implementing the intervention; interviews were conducted to determine the levels at which they continued to use the intervention; and an Innovation Configuration Map was developed to assess fidelity of implementation and guide observations. The findings suggest that teachers were unconcerned about implementing the innovation and most were no longer using it. Although the teachers' concerns were unrelated to current use, their responses indicate they chose to discontinue the practice primarily because of personal concerns and management issues. The results of this study suggest that sustainability of a promising practice can be influenced by the concerns of those prepared to use it. Those looking to establish the implementation and sustainability of a promising or proven practice first need to provide clear demonstration of how its use can be responsive to a range of teachers' concerns that could be unrelated to the practice such as teacher's sense of self, the feasibility of the task, or the impact of the innovation on student outcomes. Addressing the individual concerns of teachers could likely lead to a more sustained use of the desirable practice, especially if they are asked about their concerns with implementation early and often in the process. [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.]