This randomized clinical trial aimed to estimate the effect of adding an initial web mode to existing Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) survey protocols and extending the fielding period on response rates (RRs) and representativeness of underserved patient groups. The study included 36,001 patients discharged from 46 US hospitals from May to December 2021. Patients were randomized to one of six survey protocols: three standard HCAHPS protocols (mail only, phone only, mail-phone) and three web-enhanced protocols (web-mail, web-phone, web-mail-phone). The results showed that the web-mail-phone protocol had the highest RR (36.5%), followed by two-mode protocols (30.3%-31.1%), and single-mode protocols (22.1%-24.3%). The web-mail-phone protocol also had the highest yield for three racial and ethnic groups (Black, Hispanic, and White patients) and second highest for another group (multiracial patients). The gains from multimode approaches were often 2 to 3 times as large for Asian American or Native Hawaiian or Other Pacific Islander, Black, Hispanic, and multiracial patients as for White patients. Extending the fielding period from 42 to 49 days further improved RR and representativeness, especially for underrepresented groups. The study concluded that web-enhanced multimode survey protocols can improve response rates and representativeness of vulnerable patient groups, and the US Centers for Medicare & Medicaid Services will allow hospitals to use these protocols for HCAHPS administration starting in 2025.This randomized clinical trial aimed to estimate the effect of adding an initial web mode to existing Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) survey protocols and extending the fielding period on response rates (RRs) and representativeness of underserved patient groups. The study included 36,001 patients discharged from 46 US hospitals from May to December 2021. Patients were randomized to one of six survey protocols: three standard HCAHPS protocols (mail only, phone only, mail-phone) and three web-enhanced protocols (web-mail, web-phone, web-mail-phone). The results showed that the web-mail-phone protocol had the highest RR (36.5%), followed by two-mode protocols (30.3%-31.1%), and single-mode protocols (22.1%-24.3%). The web-mail-phone protocol also had the highest yield for three racial and ethnic groups (Black, Hispanic, and White patients) and second highest for another group (multiracial patients). The gains from multimode approaches were often 2 to 3 times as large for Asian American or Native Hawaiian or Other Pacific Islander, Black, Hispanic, and multiracial patients as for White patients. Extending the fielding period from 42 to 49 days further improved RR and representativeness, especially for underrepresented groups. The study concluded that web-enhanced multimode survey protocols can improve response rates and representativeness of vulnerable patient groups, and the US Centers for Medicare & Medicaid Services will allow hospitals to use these protocols for HCAHPS administration starting in 2025.