The purpose of this quantitative study was to further the understanding on how access to trauma-informed professional learning changed research-based practices in classroom and school-wide settings in K-12 schools. The guiding question for this quantitative study was: How has trauma-informed professional learning influenced changes in research-based practices in school-wide and classroom settings in K-12 schools? This research assessed the perceptions of elementary, middle, and high school teachers in one school district to investigate access to trauma-informed professional learning and potential changes in research-based practices in school-wide and classroom settings. Participants were teachers, in Northeast Tennessee, employed in urban schools implementing trauma-informed practices. Six research questions guided the study and quantitative data were analyzed using one-sample t-tests. Additionally, this researcher analyzed themes gleaned from the four-open ended questions at the end of the survey. The findings indicated that the means of all measures were significantly higher than the midpoint in elementary, middle, and high schools. The findings also indicated that trauma-informed professional learning supports the development of school-wide and classroom research-based practices and application of trauma-informed strategies in K-12 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.]