This 3-year-long case study describes a co-teaching model to support ELL students. The school the study is conducted within consists of students belonging to diverse cultures (largely populated by Hmong students, specifically, 80% of the students were students of color and 53 of the students are identified as ELL). In the first year of the study, job-embedded PD was implemented by the university partners, where teachers planned, taught and reflected on their teaching collectively. The results showed both teacher and student growth. Teachers who were resentful of collaboration because of the challenges it brought (such as different teaching philosophy, increased communication demand, scheduling difficulties, and sharing responsibility), became advocates of collaboration. Several factors may have caused this change; pre-existing dissonance that most of the teachers perceived that ELLs’ experience as isolated, administrative mandates combined with early support, small group instruction and co-teaching, collaborative planning, and multiple and varied instructional models. Achievement test scores showed the academic growth of students, in addition to teachers’ specific examples of students’ improved learning.