The landscape surrounding teacher evaluation is changing as teacher accountability becomes more prevalent in this process. This study looks at how teacher-created student growth assessments (SGAs) for teacher evaluation affects teacher efficacy with respect to instructional practice. Survey data were collected from 110 kindergarten through eighth-grade teachers; additional data were gathered from three interviews. A majority of these teachers reported the work in creating SGAs benefitted their instructional practice. Teachers reported increased knowledge in learning standards, curriculum development, and assessment literacy as a result of creating their own SGAs. Qualitative findings suggest that when teachers are provided an opportunity to collaborate, they learn from each other. Other findings suggest teachers may need professional development to increase their ability to collaborate efficiently and effectively.