Teachers play a crucial role in helping students develop the skills needed for success in school, career, and life. These skills--which are a focus in the Common Core State Standards (CCSS)--include higher-order thinking and complex literacy skills, such as reading, writing, and citing evidence from texts. Professional development (PD) can strengthen teachers' instructional practices to help students learn these skills, especially if the PD is paired with curriculum, intensive, sustained over a long duration, and ensures that teachers integrate what they learned. To address the need for high quality and lasting professional learning for teachers, EL Education developed the Teacher Potential Project (TPP), which includes the CCSS-aligned EL Education Language Arts Curriculum in combination with intensive PD. In an independent study funded by a U.S. Department of Education Investing in Innovation grant, Mathematica Policy Research examined a range of middle grades teachers' CCSS-aligned instructional practices after one and two years of TPP engagement. The study team found that TPP teachers demonstrated and sustained a range of CCSS-aligned instructional practices more than teachers who did not engage with the TPP. These two-year findings build on previous positive results of one year of TPP engagement. The findings are presented in this report.