Background <p>Cumulative risk assessment has become a key framework for understanding how multiple environmental and public health stressors interact, yet little is known about how these risks are communicated to the public. This study examined both professional practices and public responses to cumulative risk communication.</p> Methods <p>Fifteen semi-structured interviews were conducted with federal risk communicators, and a nationally representative online survey of 2,531 U.S. adults was fielded. The survey included an experiment comparing responses to cumulative versus single-risk messages. Qualitative data from interviews were thematically analyzed, and survey responses were analyzed using descriptive statistics and experimental contrasts.</p> Results <p>Most practitioners acknowledged the importance of cumulative risk but reported rarely communicating it, citing time pressures, institutional silos, and perceived audience cognitive limitations as barriers. Public survey results contradicted this latter assumption: a majority of respondents preferred messages that addressed multiple, interacting risks, and experimental data showed no significant differences in comprehension, prioritization, or behavioral intentions between cumulative and single-risk messages.</p> Conclusions <p>Findings reveal a disconnect between practitioner assumptions and public responses to cumulative risk communication. Closing this gap will require organizational support, accessible communication tools, and continued research to align professional practice with public preferences and capabilities.</p>