Wild free-roaming (WFR) horses (Equus ferus caballus) occur on lands administered by the Bureau of Land Management and US Forest Service in 10 western US states. Little is known about public knowledge concerning management of WFR horse populations. In 2020, we conducted a survey to assess public knowledge with the intent of establishing baseline information that may be used to shape horse management programs and policies on the nation’s public lands. We obtained responses from 1,124 residents of the western United States. Our survey asked eight knowledge-based questions of WFR horse ecology and management in the western United States. We conducted chi-square analyses to determine the influence of age, gender, region of residence, and income on respondents’ ability to answer these questions appropriately. Our results indicate that these demographic characteristics had little predictive ability to explain the level of the western US public’s knowledge of WFR horse ecology and management (for all comparisons, λ < 0.10). Furthermore, our respondents had little knowledge of WFR ecology and management. Approximately 30% of respondents correctly identified WFR horse origins, 8% correctly indicated WFR horse population size, and 37.5% indicated that they were unaware of legal management options. The lack of basic understanding of WFR horse ecology and management may influence the public’s ability to support management efforts or determine fact from propaganda. Approximately 60% of the respondents indicated they primarily used government, university, and organization websites when seeking information. Efforts to increase dissemination of facts on multiple venues, such as social media, websites, and newspapers that link back to government and university websites, could increase public support of future management actions. Additionally, the announcement of management actions, such as round-ups, should consistently include basic background information regarding WFR horse ecology and populations to ensure that the public can make informed conclusions.