This report is part of ongoing research engaged in transforming knowledge of how human communication works into improvements in man-machine communication of existing and planned computer systems. The methodology includes having a trained "Observer" annotate transcripts of human communication in a prescribed manner. One of the issues, therefore, in evaluating the methodology is the reliability of the Observer's work. This report describes a test of Observer reliability. The test showed high reliability, and indicated that the observation methods are capable of deriving information which reflects widely shared perceptions about communication. It confirms the appropriateness and potential effectiveness of using this kind of observation in the dialogue-modeling methodology. (Author/WBC)