A group of five Americans gathered in Paris a century ago to negotiate an end to the Spanish-American War. President William McKinley had already decided to take the Philippines from Madrid's decrepit empire but had cunningly included in the peace delegation two men of anti-imperialist persuasion (to be outvoted by the others if necessary), so he might appear modest and even hesitant in making his large demands.

The real force in the U.S. group was onetime GOP vice-presidential candidate Whitelaw Reid of the New York Tribune, an unabashed expansionist. As Reid relates in his published diary, Spain's ambassador to France begged him: "Do not forget that we are poor; do not forget that we are vanquished; do not forget that after all it was Spain that discovered America; do not forget that this is the first great war you have had with a nation on the continent of Europe, or with any foreign nation; that you have had an astonishing victory, and that you cannot complete it without showing magnanimity." Reid, unmoved, intended to have the United States act the part of a great power. He meant to see McKinley's instructions--issued in installments to accentuate the President's image of gravitas--carried out: take the Philippines, Puerto Rico, Guam, and effective control of Cuba. He approved when the U.S. delegates deliberately sat so that the late afternoon sun would blaze through the large Quai d'Orsay windows directly into the faces of their Spanish counterparts. No one could now mistake who held the whip hand.

Not all Americans were appreciative of this power display. Anti-imperialist steel baron Andrew Carnegie wrote Reid about his "War Treaty with Spain . . . It is a matter of congratulation . . . that you seem to have about finished your work of civilizing the Fillipinos [sic]. It is thought that about 8000 of them have been completely civilized and sent to Heaven. I hope you like it." Anti-imperialists put up a strenuous campaign against Reid and McKinley's treaty, and senators narrowly approved it only after being shocked by news of the beginning of the Filipino "insurrection" historians today call the U.S.-Philippine War. McKinley and the expansionists carried the day but before long tacitly agreed with the "antis" that colonialism was not America's cup of tea. By 1907, the Rough Rider President, Theodore Roosevelt, considered the Philippines the "heel of Achilles" of U.S. policy in Eastern Asia.

Colonialism might be cast aside, but not so the pursuit and exercise of international power. T.R., writes historian H. Wayne Morgan, was "the first president to have no rest from complicated foreign issues, just as his generation of Americans was the first to pursue more than 'crisis diplomacy.' Foreign affairs were here to stay." A United States continuously engaged in world affairs was a remarkable development. McKinley and Roosevelt had abandoned the conceit that America was immune to the machinations of those acting on the world stage. Historians and political scientists have long puzzled over how long it took them to do so, for in size, population, and wealth, the American nation was a power of consequence well before 1898.

Political scientist and managing editor of Foreign Affairs Fareed Zakaria approaches the puzzle in From Wealth to Power by taking readers along two paths. The first carries them to the turbulent waters of international relations theorists' debates over "realism", where he inserts his own long oar. The second path leads to an explanation of how a government that raised hundreds of thousands of troops and built a first-rate navy to defeat the Confederacy could then revert to a Lilliputian among the Brobdingnagians of world politics, an explanation embodied in a revised narrative of American diplomatic history from 1865 to the close of Roosevelt's presidency.

The responses of readers will depend partly on which highway particularly appeals to them. Most intriguing to this historian is the second. The temporal lag between American social, political, and economic development and the U.S. emergence as a world power is a perennial analytical challenge. And the possibility that a successful response to that challenge might provide a fresh story line should cheer anyone weary of the textbooks, op-ed pages, and television "specials" still stereotyping the Spanish-American War as the product of an out-of-control public opinion, the "yellow press", and a craven McKinley.

The ultimate importance of Zakaria's book, however, lies in its contribution to the international relations debate. He distinguishes among three kinds of "realism." "Classical" realism "supposes that a nation's interests are determined by its power" vis-a-vis others, and that nations "expand when they can" and "when their power is on the rise." "Defensive" realism, in contrast, posits "that states seek security rather than influence" and, therefore, that "nations expand their interests abroad when threatened" by "powerful nations with aggressive intentions." Nations act forcefully "not when they can but when they must."

The author exposes the inadequacy of either of these two brands of realism to explain why an already powerful American nation acted reticently on the world scene after the Civil War, but, as a far more powerful nation, suddenly and impressively asserted itself at the end of the century. The classical school cannot explain the 1860s-80s passivity without denying (against irrefutable evidence) how powerful the American nation had already become. Rebutting the defensive theory, Zakaria contends, is the fact that post-Civil War American policymakers retreated before threats, while those who guided the later drive to expansionism acted in the absence of serious threats.

Zakaria advances a third, "state-centered" realism to explain what classical and defensive realism cannot, and to solve the time-lag puzzle. Why did expansionism occur long after the American nation had grown powerful? Part of the answer, he maintains, lies in distinguishing between powerful nations and powerful states. It is the latter, run by "decision-makers", that build armies and navies, make wars, and seize overseas territories. Decision-makers, however, can act forcefully only when wielding the organs of a powerful, or at least competent, state capable of drawing on national power and wealth to effect policy. State-centered realism, which reinforces rather than rejects the "classical" version, holds that "statesmen will expand the nation's political interests abroad when they perceive a relative increase in state power, not national power." When a state's ability to draw on national power grows, so does its "capacity and cohesion to carry out its wishes." Without "centralized decision-making and . . . access to material resources, no state can be considered strong." In the United States, state power grew in response to industrialization, eventually generating the supremacy of the federal over state and local governments and, within the federal government, the presidency and executive bureaucracy over political parties and Congress. This process had gone far enough in the 1890s for McKinley to seize the Philippines and, thereafter, for T.R. to fulfill the dreams of the arch-expansionist of the 1860s, Secretary of State William Henry Seward.

If correct, Zakaria's theory would explain a great deal and further stir the waters of the international relations theorists. In its support, he tallies every "opportunity" for "expansion" between 1865 and 1908, how American leaders responded to each, and how his theory accounts for each of their choices. Throughout this era, he argues, "central decision-makers . . . expanded American influence abroad when they perceived increases in state power."

State-centered realism is a theory about the making of foreign policy, not about the results of policies or their cumulative impact on the international system. This is not a serious shortcoming, but there may be others. Apart from specifics--Zakaria's dubious view, for example, that Seward's deft delay in forcing France out of Mexico was a case of the United States drawing in its horns, or that Washington backed down during the 1895-96 Venezuela crisis--his theory and its application raise more questions than answers. The assumption that we must choose between state-centered and defensive realism, that "the foreign policy behavior of a rising state" will revolve around either "state power or the level of external threat", is unconvincing: Why not both? It is also unfortunate, given how many ways states have discovered to gain influence and "expand", that Zakaria insists on territorial acquisitions as the "ultimate measure of international influence in the late nineteenth century", which by definition bars reconsideration of the belief that the United States became a "power" only in 1898.

Except for the concession that no theory can cover all cases, Zakaria also cannot account for such lurches in foreign policy behavior as those from Hoover to FDR and Carter to Reagan. In both cases, the chief "decision-maker's" view about the need to conduct a strenuous foreign policy shifted from something like indifference to urgency. A metallic clang in the theory, and Zakaria's persistent underestimation of culture, ideas, and ideology in shaping foreign policy, are at the root of the problem. Saying that McKinley & Co. went expansionist on discovering they could is like saying that Kennedy and Johnson went into Vietnam when they had enough troops and airlift to do so. Capacity is important, but surely not that important. Herbert Hoover's ideology-driven suspicion of building up a centralized state had more to do with his policy than pessimism about the state's capacity to act. Can Carter's and Reagan's different perceptions of their ability to draw on state power explain anything about their differences? Far less, I would think, than examining side by side Carter's determination to abandon an "inordinate fear of communism" and Reagan's ideology-driven resolve to vex, harass, and annoy the Soviet Union.

Nonetheless, Zakaria's quest for analytical precision and a recast narrative is unpretentious and engagingly written. His book is stimulating to the end. As state capacity crumbles in Russia and grows in China, readers should ponder his view that the gradual loss of the nation-state's power and autonomy, evident over the last 150 years, might in the twenty-first century "blunt the otherwise aggressive temperament of great powers and tame the fierce nature of international life."