There is evidence from previous census years that the decennial census has an impact on American Community Survey (ACS) response rates, with ACS response increasing before census day and decreasing after census day. This may be because some respondents do not recognize that they are being asked to respond to two distinct requests from the Census Bureau. In 2010, the use of messaging in ACS materials explaining that the survey is different from the census improved ACS participation compared to the standard production materials. Therefore, an interdivisional Census Bureau team made similar updates to the ACS materials for 2020 which were then cognitively tested with 20 participants. Overall, the revised materials were successful at distinguishing the ACS from the 2020 Census and communicating that response to both is mandatory. Most of the recommended language was implemented into materials that were planned for the March-September 2020 ACS panels. However, mailing constraints related to the COVID-19 pandemic resulted in modifications to this plan for the April-September 2020 ACS panels. Because of this, we recommend conducting additional testing prior to 2030 to inform decisions about their use.