The agenda-setting concept in mass communication asserts that the news media determine what people will include or exclude in their cognition of public events. Findings in uses and gratification research provide the foundation for this concept: an initial focus on people's needs, particularly the need for information. The agenda-setting concept reflects the media's three operating characteristics as analyzed by Noelle-Neumann: (1) ubiquity-the pervasive presence of mass media; (2) consonance-the tendency of professional communicators to produce similar details, viewpoints, and emphases when reporting on an issue, event, or person; and (3) cumulation-the continuing treatment of a topic in the press. Denying that the media has immediate effects on public attitudes, agenda-setting aligns itself with a diffusion, or multiple-step flow, model that stresses the importance of interpersonal contacts in determining the effect of media content on people. The agenda-setting concept provides communication theorists with an organizing principle for integrating scientific findings into a mass communication theory. (MAI)