The early pioneers of psychoanalysis often behaved more like followers of a religious sect than like scientists. The author attempts to view sectarian tendencies as a behavioral pattern that tends to emerge among scientists under certain types of conditions. First, the early psychoanalytic movement is used to isolate the specific factors that encourage scientific groups' sectarian tendencies. Then, the history of the movement is analyzed in terms of the effect of these tendencies. The author argues that certain unique features and events in the history of the movement resulted from the interaction and conflict between sectarian characteristics, the norms of science and the institutional imperatives of scientific life.