The most effective way to increase students' academic performance is to improve the instructional practices of their teachers. Effective, research-based instruction responsive to individual students' unique needs is imperative for quality outcomes, particularly for students with disabilities. The high-leverage practices (HLPs; Collaboration, Assessment, SEL/Behavior, and Instruction) developed by the Council for Exceptional Children are a set of practices fundamental to student success that early-career teachers should learn, implement, and teach. This exploratory descriptive study was an examination of early-career teachers' knowledge and use of the 22 HLPs. The study results indicated that similar percentages of early-career alternative-route-to-licensure and traditionally prepared teachers know and use the 22 HLPs, a finding also true for elementary and secondary teachers. Where teachers learned the HLPs showed more variation across subgroups. Focus group interviews showed that the label of HLP was unfamiliar to many of the teachers, who were more aware of evidence-based practices. Many of the early-career teachers' comments related to best practices indicated more time spent in survival or management mode than engaging in strong instructional practices. The findings indicated recommendations for practice and future research. Improving teacher preparation, professional development, and classroom implementation of HLPs could be a significant tool for improving student outcomes and closing the research-to-practice gap. By learning and teaching the four categories of the 22 HLPs, teacher educators could create preparation programs that clearly address what preservice teachers will practice in their field experiences and professions. Future researchers could build upon this study's self-reported data with observations, using HLP checklists or matrices to measure how frequently early-career teacher implement HLPs. Expanding the population to include seasoned special education teachers and educators from multiple school districts would provide greater insight into teachers' knowledge and use of HLPs and present more generalizable results. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]