Media coverage of collective traumas may trigger psychological distress in individuals outside the directly affected community. We examined whether repeated media exposure to the Boston Marathon bombings was associated with acute stress and compared the impact of direct exposure (being at/near the bombings) vs. media exposure (bombing-related television, radio, print, online, and social media coverage) on acute stress. We conducted an Internet-based survey 2–4 wk postbombings with a nationally representative sample and representative subsamples from Boston and New York (4,675 adults). Repeated bombing-related media exposure was associated with higher acute stress than was direct exposure. Media coverage following collective traumas can diffuse acute stress widely. This unique study compares the impact of direct vs. indirect media-based community trauma exposure on acute stress responses.