This report presents the findings from an independent evaluation conducted by WestEd on the Expository Reading and Writing Curriculum (ERWC). Funded by an Investing in Innovation (i3) Validation grant, the ERWC is a grade 11 and grade 12 English language arts (ELA) curriculum developed by the California State University. The independent evaluation includes an evaluation of the fidelity of implementation of the curriculum and an impact evaluation that took place during the 2020/21 school year. The fidelity of implementation evaluation found that a high percentage of teachers participated in the professional learning with fidelity but that few teachers taught the full curriculum with fidelity, and these results were due to many factors, including time constraints and shifts in instruction due to the COVID-19 pandemic. The grade 11 impact evaluation found that assignment to the ERWC had a positive and statistically significant impact on student achievement as measured by the Non-Performance Task Interim Comprehensive Assessment; however, no statistically significant impact was detected among the students who took the Smarter Balanced Summative Assessment. In the grade 12 impact evaluation, there was no statistically significant difference in achievement between students who had enrolled in the ERWC and students who had enrolled in the comparison English course. Further evaluation of the ERWC in a non-pandemic year during which schooling takes place in person is recommended.