To the best of my knowledge, Robert Service’s “Comrades!” (Harvard University Press, 592 pages, $35) is the first history of world communism. It includes every communist state, extinct and surviving, as well as major communist parties and movements around the world. It is a daunting undertaking that required mastery of vast amounts of source materials and the skill to make judicious choices among them. Mr. Service, a British historian has written a great deal about the Soviet Union, including biographies of Lenin and Stalin, which provide a useful point of departure. He makes use of archives, memoirs, and large numbers of “further sources” in several languages. The book is organized in chronological order around six topics: Origins, Experiment, Development, Reproduction and Mutation and Endings.

Four major questions are addressed. First, what did these systems have in common? Was, or is there such a thing as “communism” — a coherent phenomenon that appeared in countries as different as Albania, China, Cuba, Czechoslovakia, North Korea, and the Soviet Union, among others? Second, why and how did these systems come into existence? Third, why and how they collapsed (or, in a few instances endured)? Fourth, why did they inflict so much suffering on so many people?

Mr. Service’s major finding, far from self-evident, is that “despite all the diversity of states committed to communism there was an underlying similarity in purpose and practice.” All communist states controlled the economy, and introduced, at some stage or another, mandatory worship of a supreme leader supposedly endowed with super-human virtues and qualifications; all sought to eliminate traditional religious practices; all restricted contacts with the non-communist world. Each developed large and highly specialized police forces to deal with political deviance — genuine, potential, or imaginary. This last feature was an especially important. “Communism,” Mr. Service concludes, “had been held together by force.”

The similarities among systems were also rooted in their shared commitment to Marxism. Even if the emerging practices and policies came to diverge from the ideals of Marx, all these states were faithful to at least some of his doctrines. They shared, for example, the unwavering (and wrongheaded) conviction that eliminating the private ownership of the means of production was the precondition for a vastly improved social system and better human beings.

The discontents inspired by the failings of these systems were also remarkably similar. They included recurring shortages of food, consumer goods, and housing; the strenuous efforts to subordinate the personal to the political realm; the persistent infringements of traditional values and beliefs; the restrictions on free movement; the privileges of the political elites; inundation with propaganda that misrepresented reality; and the fear of the brutality wielded by the police state.

Once the will to repression diminished, these systems fell apart. Those that did not (Cuba, China, Vietnam, and North Korea) retained vigorous policies and institutions of repression. Mr. Service also correctly points out that these systems could not be reformed. “Any process of reforming communism,” he writes, “is likely to turn into a movement to transform it into something radically different.”

The author is especially helpful in explaining the part Marxism played. In the first place it whetted appetites for utopian political arrangements and social engineering without providing blueprints for them. Most importantly, it “contained seeds of oppression and exploitation” by nurturing intolerance and ruthlessness among the revolutionary leaders: The glorious ends justified sordid means. Several major propositions of Marxism were wrong or inapplicable in the 20th century. Capitalism did not retard the forces of production and was not the source of all evil. Crushing capitalism was not going to change the human condition — there were clear limits to the perfectibility of human beings and social institutions.

I have only two minor criticisms. The chapter on Marx and Engels relies too heavily on David McLellan’s book, “Karl Marx: His Life and Thought” (1973), while making no reference to arguably more important authors such as Leszek Kolakowski, Isaiah Berlin, and Alexander Yakovlev, among others, who also had much to say on the subject. Yakovlev does not even appear in the bibliography. The second criticism concerns two proposition about Cuba. The first that “a failure of mutual accommodation” between America and Castro “produced the first communist state in the Americas” is a dubious oversimplification. I also disagree with the observation that while political prisoners were treated harshly “practices usually stopped short of physical torture.” The memoirs of numerous former such prisoners suggest otherwise.

“Comrades!” is otherwise a rich repository of information and insight and should be required reading in institutions of higher education around the world.

Mr. Hollander’s books include “Political Pilgrims” (1981), “Political Will and Personal Belief: The Decline and Fall of Soviet Communism” (1999), and “The End of Commitment: Intellectuals, Revolutionaries and Political Morality” (2006).