Some of the major assumptions, empirical inferences, and theoretical linkages that underlie the generalization that interpersonal influence is more efficacious than mass communication in bringing about social change are examined in this paper. The central premise of the paper is that the presumed competition between mass and interpersonal channels is a synthetic one, created by observers who reify "channel effects" based on the ways sources of messages, rather than receivers, utilize different channels. The paper argues that people's relative reliance on information from mass or interpersonal channels as a guide to behavior is not strongly modified by channel characteristics and is not a reliable indicator of channel-oriented motivations or preferences. It contends that instead, channel use is determined mostly by structural factors in the organization of a person's information environment. The paper further argues that the sources a person consults for information relevant to a personal decision are determined mainly by their accessibility and by the likelihood that they will contain such information. (FL)