There are currently over five million multilingual learners (MLs) in U.S. schools (National Center for Educational Statistics, 2018). Yet, most teachers have not received adequate or effective professional development and therefore do not possess the knowledge and skills needed to improve student achievement with this population. A lack of preservice coursework and ongoing, effective professional development for teachers in evidenced-based instruction and culturally responsive practices may be contributing to the achievement gap between high needs populations and non-high needs populations (Gandara, 2013; Darling-Hammond, 2017; Haas & Brown, 2019). The increasing cultural, linguistic, and educational diversity of today's students necessitates changes to the policies regarding pre-service teacher requirements and approaches to in-service teacher professional development that will result in increased teacher efficacy in meeting the needs of multilingual learners. This quantitative secondary analysis of archived data from the Teaching and Learning International Survey (TALIS) conducted by the Organization for Economic Co-operation and Development (OECD) in 2018 examined the relationship between certain types of structured professional learning opportunities, including pre-service coursework, coaching, collaboration, and feedback, with secondary teachers' feelings of self-efficacy in meeting the instructional needs of multilingual students in a multilingual general education classroom. [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.]