Until recently, political scientists and émigré journalists have done most of the work on Soviet political history. Some of their work has been very good, but it seemed to me that the subject could benefit from a historian's treatment. I therefore approached this study with a distrust of preconceived models and abstract constructs and with the goal of setting out exactly what happened in the Bolshevik Party in the thirties.

Avoiding the standard concentration on Stalin's personality, this work aims to rationalize our understanding of the period by evaluating structural, institutional, and ideological factors. I have tried to provide an interpretive framework that reflects the available documentary evidence and accounts for the often mysterious events of the thirties. I believe that it explains more and contradicts itself less than other reconstructions. Because of the nature of this field, no one can avoid speculations and guesswork about the origins and course of historical events. But in my view, interpretations based on critical use of the internal records of the participants are better grounded than those that rely on the literary memoirs of courageous but exogenous victims of the process.

Many of the people whose opinions I value were able to read and comment on all or parts of this study. I owe special thanks to my mentor and adviser Roberta Manning, whose energy, patience, and enthusiasm lasted through several drafts of the work.