Why did the Soviet system fail? How is it that a political order, born of revolution, perished from stagnation? What caused a seemingly stable polity to collapse? Philip Roeder finds the answer to these questions in the Bolshevik "constitution"--the fundamental rules of the Soviet system that evolved from revolutionary times into the post-Stalin era. These rules increasingly prevented the Communist party from responding to the immense social changes that it had itself set in motion: although the Soviet political system initially had vast resources for transforming society, its ability to transform itself became severely limited. In Roeder's view, the problem was not that Soviet leaders did not attempt to change, but that their attempts were so often defeated by institutional resistance to reform. The leaders' successful efforts to stabilize the political system reduced its adaptability, and as the need for reform continued to mount, stability became a fatal flaw. Roeder's analysis of institutional constraints on political behavior represents a striking departure from the biographical approach common to other analyses of Soviet leadership, and provides a strong basis for comparison of the Soviet experience with constitutional transformation in other authoritarian polities.