A conceptual approach to studying interpersonal influence is outlined as a framework within which results of a study of purchase decisions in business firms are presented. Data concerning the bases of influence in these organizations--especially data showing the importance of a person's stake in the decision--do not fit neatly into the well-known influence categories proposed by French and Raven. Disagreements among informants about who had most influence on each decision also raises questions about the general applicability of certain often-used measures of influence in organizations. (Author)