This article reports on a mixed-methods study of Washington state principal professional development (PD) needs focused on supporting English learner (EL) students. With a growing number of EL students, a heterogeneous group that represents a variety of language, cultures, and experiences, it is imperative to understand what principals need as they drive change and set the tone for teachers and their schools. Twenty-three principals were surveyed using the English Language Learner Program Survey. A subsample of seven principals was also interviewed to explore areas of need. Descriptive analysis of survey results revealed differentiated instruction, family and community involvement strategies, and culturally responsive teaching as the top three areas of PD needs. Thematic analysis of follow-up interview data illustrated the many challenges principals face, such as limited resources and the school climate, when serving EL students. These trends have informative implications for school site leadership regarding the need for professional learning opportunities focused on supporting EL students. However, replication is needed in a larger sample to truly determine the significance of these findings.