Usability testing was performed on 15 prototypical screens with limited functionality (i.e., wireframes) comprising an initial version of an online version of the American Community Survey (ACS). The wireframes for Rounds 1 and 2 were identical and the same protocol was followed for each round. The wireframes were tested alone in the first round, and the mailing materials for ACS Internet experiment were tested along with the wireframes in the second round of wireframe testing. The panels for the second round of testing matched the five panels fielded in the 2011 ACS Internet Test: Prominent Offer (Choice), Not Prominent Offer, Push Internet, Push Internet Modified Schedule, and Control (Production – no Internet option). Participants were randomly assigned to read one of the five sets of materials for one panel condition and then they used the materials to access the online wireframe instrument. For the Control condition, the mailing materials offered no option for taking the survey online, so participants were given materials from one of the other panels in order to access the online survey. The results from the 2011 ACS Internet Test will be used in planning for an Internet response option in the 2020 United States Census.