To provide quality education to all students, including ELLs, teachers need professional development designed and enacted according to best practice. However, a common problem for professional development is that teachers' practices often do not change. Implemented through the partnership collaboration with university, education, and public school faculty, the professional development designed in this study focused on educating teachers about needed content and engaging them in ways that would increase the likelihood they would enact such practices in their classrooms (Desimone, 2009; Opfer & Pedder, 2011; Penuel et al., 2007). The professional development program comprised six courses that adhered to the Utah State Office of Education's standards for the education of the teachers of ELLs. The study examined the teachers' beliefs and their classroom practices. A total of 197 teachers were surveyed on their beliefs toward teaching ELLs, and a subset of 23 teachers' classroom practices were videotaped. Factor analyses were conducted on the pre- and post-survey. The videos were coded using a protocol based on the SIOP model (Echevarria et al., 2013), and latent variables were created to measure the change of the survey score and practice score. The analysis revealed that teachers' beliefs or knowledge in particular changed from when they began the course of second language acquisition to the time they completed it. In addition, teachers' practice changed from the time they started the professional development program to the time they completed it. However, even though teachers' beliefs and practices changed, there was no correlation found between the belief change and the practice change. This study adds to the literature that educating teachers about second language learning and research-based practices (Baker et al., 2014) using professional development that attends to teachers' practices as well as their beliefs (Desimone, 2009; Opfer & Pedder, 2011; Penuel et al., 2007) resulted in positive changes in teacher's beliefs and practices for teaching ELLs. Future research should add a variable of teacher's beliefs about the context of their teaching practice into the study for this can be a confounding variable that affects the correlation between the change of beliefs and the change of practices.