The purpose of this qualitative study was to explore how one Southern California elementary school approached family engagement for English learners (ELs) in a culturally proficient manner. School leaders are in unique positions to create cultures of success and inclusion for all students, especially for EL students. One of the best ways to understand students is to know their families. Strong collaborative partnerships between families and schools are crucial to fostering increased EL family engagement. This study used the five essential elements of the cultural proficiency framework (CPF) as a theoretical framework. The goal of the CPF is for educators, especially teachers, to understand, embrace, and talk about cultural differences so schools can recognize and respect individuals and their cultures. Cultural proficiency is a model for shifting the culture of a school and for individual transformation and organizational change. This case study focused on one elementary school, Cooper Elementary, located in a predominantly Latinx community, with 29% ELs; 92% of the EL population at Cooper Elementary spoke Spanish. This single elementary school case study consisted of three data sources: eight one-on-one interviews with school staff, nine one-on-one interviews with mothers of EL students, and 45 documents related to school--home communications. Findings from this study helped the researcher gain a deep understanding of the perspectives of staff and families on engagement of EL families and the role cultural proficiency plays in EL family engagement. Findings from this study highlighted successes and barriers related to engagement. Findings are organized thematically by five significant themes that emerged from the data: Language, Relationships, Input, Opportunities From Involvement, and Valuing Cultural Proficiency. This study also contains recommendations for practice, policy, and future research related to culturally proficient practices that support EL family engagement in elementary 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.]