The natural history--including psychiatric symptoms, precipitating factors, onset and course of illness, and personality characteristics--of 47 social phobics, 80 agoraphobics, and 72 simple phobics was examined. The social phobia group differed from the agoraphobia group by having a lower mean age, fewer females and married members, and a higher educational and occupational status. They were less fearful generally, less obsessive, and less likely to follow a fluctuating or phasic course. There was overlap between the two groups with regard to main phobias, and they were similar with regard to adjacent symptomatology. Both the social and agoraphobia groups differed in similar and significant ways from simple phobics.