DescriptionThe purpose of this systematic qualitative research investigation was to pilot a vertically aligned professional learning community (PLC) to improve teacher collaboration across grade levels and to inform effective vocabulary instruction. This research intervention was conducted at the Dream Big primary school, which serves a large population of English Language Learners (ELL). Reading can be a challenge for the ELLs at the primary school because of limited English language acquisition and lack of basic and academic vocabulary. In order to meaningfully design and implement vocabulary instruction that better meets the needs of the students, teachers need to understand the progression of vocabulary instruction. For this type of cohesion to occur, teachers need time to collaborate across grade levels. A collective case study design was utilized to explore and examine teacher experiences with participating in a vertically aligned PLC focused on vocabulary instruction. A case study design allowed for an in-depth exploration of the vertical PLC sessions. Data sources in the study included an initial questionnaire, facilitator observations of each session, a collection of documents and artifacts, participant reflection forms, and two final focus group interviews. The participant sample included one ESL teacher from each grade from kindergarten through third grade, two ESL teachers who work across different grade levels, and one ESL teacher that works with the Special Education classrooms.