This proposal seeks to describe and explain patterns of electronic media selection and use in settings where individuals have access to two options, voice messaging and electronic mail, as well as traditional communication channels. The research will provide an improved understanding of the perceived advantages and disadvantages (e.g., ease of learning vs. efficiency) of these communication media and it will provide new insights into the ways in which media selection affects the organizational setting. The project will develop a model of choice between media alternatives and it will test this model in an ambitious field investigation that will employ both quantitative and qualitative methods to examine electronic media usage patterns at the individual, departmental, and organizational levels of analysis. The three proposed explanations for media choice behaviors (rational choice, critical mass, and social influence) are considered to be of general interest, in terms of how individuals and groups make choices among competing or complementary alternatives, as well as of specific interest in the context of media-use decisions.