Since its inception in 2005, the American Community Survey (ACS) has used multiple methods to collect responses, including paper questionnaires, phone interviews, in-person interviews, and, since 2013, online responses. The U.S. Census Bureau sends mailings to encourage self-response—an approach known as the self-response or mail contact strategy.  ​

​This document summarizes findings from Census Bureau research, spanning more than two decades, on the ACS self-response contact strategy. It includes research that led to successful changes to the contact strategy and materials, as well as research that did not, and a discussion of current and future testing. The document is intended to serve as a comprehensive reference, enabling readers to efficiently review the vast body of research to improve the ACS program's survey contact strategy over the past two decades.