During the last 60 years, the United States (US) has experienced a rapid growth of MLLs (multilingual learners), also known as ELLs (English Language Learners) or English as a Second Language (ESL) learners. These students represent a large segment of the public education population, and there is an academic achievement gap between MLLs and non-MLLs as shown through graduation rates. With the expanding MLL population and achievement gap between the MLLs and non-English learners, teachers are given little to no formal training in teaching MLLs. This qualitative study examined topics for professional development (PD) opportunities for a school in a southeastern Pennsylvania School District through in-depth, semi-structured interviews with teachers. This study evaluated experiences from teachers and teachers' aides to determine factors in the discrepancy in academic performance between MLLs and non-MLLs. The PD topics included teacher collaboration, MLL specific technology, diversity, equity, inclusion and belonging (DEIB), and parent communication. The emerging themes from research included: providing staff with practical PD on universal adaptations to implement on multilanguage learners; providing periodic follow-ups throughout the year; collaboration with English language development teacher; practical PD on MLL specific technology; instilling a sense of belonging for MLLs through the sharing of personal narratives; and increasing MLL parent involvement and communication. The researcher presented to the district the plan for the series of PD topics for teachers to promote the academic success of MLLs. [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.]