The historical independence of expert power and opinion leadership research and theorizing is noted, with the major credit for the separateness being attributed to differences in methodological approach usually taken in the two areas of research. A theoretical attempt to relate the two areas is make by relating: (1) the general areas of social power and leadership, (2) expert power (a sub-area of social power) to leadership, and (3) expert power to opinion leadership (a sub-area of leadership). Historical evidence for the relationship of opinion leadership and expert power is cited, culminating in some theorizing and research that crosses the usually inviolate methodological lines that have historically separated the two areas of research. References are included. (Author)