Applying multimodal textual analysis to the languages and images of on-line communication forms, Kay Richardson shows, from an applied linguistic perspective, how the Internet is being used for global, interactive communication about public health risks. Detailed case studies of the possible risks posed by SARS, by mobile phones and by the vaccination of babies against childhood diseases are situated within the context of research on computer-mediated communication, as well as within the broader social context of globalization and discourses of risk and trust.