A randomized clinical trial evaluated the impact of adding a web mode to existing HCAHPS survey protocols on response rates (RRs) and representation of underserved patients. The study involved 36,001 patients discharged from 46 US hospitals between May and December 2021. Patients were randomized to six survey protocols: three standard (mail only, phone only, mail-phone) and three web-enhanced (web-mail, web-phone, web-mail-phone). The web-mail-phone protocol achieved the highest RR (36.5%) and yield, particularly for Black, Hispanic, and White patients. Two-mode protocols (web-mail, web-phone, mail-phone) generally performed second best. Web-mail-phone showed the highest yield for three racial and ethnic groups and second highest for multiracial patients. The mail-only protocol had the lowest yield for Black, Hispanic, and multiracial patients, while phone-only had the lowest for White patients. Gains from multimode approaches were often 2-3 times larger for underserved groups compared to White patients. Web-mail-phone had the highest RR for six of eight age groups and four of five service line-sex combinations. The study found that extending the survey period from 42 to 49 days improved RRs and representation, especially for underrepresented groups. The results suggest that web-first multimode surveys can improve RRs, reduce costs, and support equity-focused quality improvement efforts. The US Centers for Medicare & Medicaid Services will allow hospitals to use web-mail, web-phone, and web-mail-phone protocols for HCAHPS administration starting in 2025.A randomized clinical trial evaluated the impact of adding a web mode to existing HCAHPS survey protocols on response rates (RRs) and representation of underserved patients. The study involved 36,001 patients discharged from 46 US hospitals between May and December 2021. Patients were randomized to six survey protocols: three standard (mail only, phone only, mail-phone) and three web-enhanced (web-mail, web-phone, web-mail-phone). The web-mail-phone protocol achieved the highest RR (36.5%) and yield, particularly for Black, Hispanic, and White patients. Two-mode protocols (web-mail, web-phone, mail-phone) generally performed second best. Web-mail-phone showed the highest yield for three racial and ethnic groups and second highest for multiracial patients. The mail-only protocol had the lowest yield for Black, Hispanic, and multiracial patients, while phone-only had the lowest for White patients. Gains from multimode approaches were often 2-3 times larger for underserved groups compared to White patients. Web-mail-phone had the highest RR for six of eight age groups and four of five service line-sex combinations. The study found that extending the survey period from 42 to 49 days improved RRs and representation, especially for underrepresented groups. The results suggest that web-first multimode surveys can improve RRs, reduce costs, and support equity-focused quality improvement efforts. The US Centers for Medicare & Medicaid Services will allow hospitals to use web-mail, web-phone, and web-mail-phone protocols for HCAHPS administration starting in 2025.