THE FOURTH VOLUME of Robert A. Caro’s The Years of Lyndon Johnson—the collective title for the still unfinished, seemingly never-ending saga, which is a profoundly eccentric and unbalanced account as well as the finest biography yet written of a 20th-century American political figure—chronicles LBJ’s life from 1958 to the passage of the Civil Rights Act, in July 1964. It follows Johnson as he clumsily seeks the Democratic presidential nomination in 1960; as he is outmaneuvered by John F. Kennedy; as he relinquishes the awesome position he had built for himself as the most powerful Senate majority leader in American history to become JFK’s vice president (and hence an impotent toady in an administration that scorned him)—and as he has the presidency thrust upon him following Kennedy’s murder. It’s a largely familiar story, and one in which, until the final months examined in this volume, its subject is perforce and atypically more acted-upon than acting. Furthermore, this volume and its predecessor—Washington-centric chronicles that cover the years when LBJ came to the fore of national life—lack the richness and vividness of Caro’s first two volumes, set largely in Texas and examining Johnson’s family background, impoverished and striving youth, and political emergence.

Still, Caro’s account takes a crucial turn here. The author has always promised that his multivolume work would reveal the dark and light sides of his subject—a man who possessed perhaps the most idealistic vision of government of any American president, and a man of staggering energy, but also a man of crushing ambition, shocking crudeness, unremitting dishonesty, and unrepentant cruelty. Until this volume, Caro, as his critics have charged, has mostly revealed the darker aspects of Johnson’s character and actions. But in this book a good deal of light emerges. This volume presents a sympathetic picture of the self-abasing and atypical—indeed slavish—loyalty that Johnson tendered to Kennedy, even as he was snubbed and disdained by such thuggishly pseudo-glamorous JFK hangers-on as that poisonous gossip Arthur Schlesinger Jr.

The dramatic centerpiece of this work is Caro’s depiction of the period following JFK’s assassination, when Johnson rose to the chaotic and potentially dangerous occasion with uncharacteristic grace, sensitivity, and self-possession—and with highly characteristic, if nonetheless preternatural, political adroitness. Caro plainly admires LBJ’s skillful exploitation of the fleeting sense of national unity to push through a crucial tax cut and historic civil-rights legislation.

Nevertheless, as in his earlier volumes, Caro is far more generous, even adoring, toward Johnson’s rivals and enemies—in this case Robert F. Kennedy and his doped-up, mobbed-up brother—than he is toward Johnson himself. Whether RFK—who shared with Johnson a mutual loathing and who, until November 22, 1963, enjoyed a near-universal and well-deserved reputation for viciousness—really underwent a characterological and ideological conversion after his brother’s murder, from McCarthyite bully-boy to, as Caro would have it, compassionate, tousle-haired hero with a “passion for social justice,” is a debatable proposition. But however one decides that question, one’s chief source should probably not be what apparently was Caro’s: the sycophantic and obviously biased account by Ben Bradlee, that tough-guy manqué with the fancy English shirts and an all but professional Friend of the Kennedys. Caro does note that the tendentious and fawning version of Camelot and its legacy advanced by Schlesinger, Bradlee, Ted Sorensen, and their ilk has become the historical template that is more or less still followed today. But the reader too often finds Caro adhering to that template himself—and one longs for him to subject Johnson’s adversaries to the same skeptical, even cynical, probing to which he has unmercifully subjected Johnson.

With this volume, however, Caro has given LBJ something of a reprieve. One suspects that this more generous treatment will continue for the first part of the next installment, which will cover Johnson’s historic 1965 Voting Rights Act and his Great Society programs. But with Vietnam—“that bitch of a war,” as Johnson called it in despair—I suspect Caro will resume his full-bore and somewhat uncharitable indictment.

THIS FAT—TOO FAT—BOOK examines ExxonMobil’s activities and evolution from 1989 to 2010. Steve Coll, the president of the Washington, D.C., think tank the New America Foundation and a writer for The New Yorker, outlines many of the political and policy challenges confronting one of the world’s largest and most powerful multinational corporations, including the enormous environmental-cleanup effort following the Exxon Valdez disaster; geopolitical instability; the promise of alternative fuels and the regulatory difficulties they pose; and the corporation’s fraught relationships with Congress, federal regulators, four presidential administrations, a host of foreign governments, and human-rights and environmental groups.

As this catalog and the book’s title and subtitle suggest, the author’s concerns largely emanate from inside the Beltway, and they more closely echo the agendas of international policy conferences than they do those of bank and corporate board meetings. Such an approach is sometimes illuminating, but it has its limitations: Coll is more successful at delineating, say, the tortured evolution of ExxonMobil’s understanding of and response to climate change than he is at dissecting its globe-spanning business strategy or its corporate culture (for a model of a probing, deeply reported book on the economics and anthropology of an iconic American corporation, readers should turn to Donald R. Katz’s now-dated 1987 examination of Sears, The Big Store). The result is a book about a colossal business that skimps on much of the business. And so Coll’s detailed account of the goings-on at ExxonMobil’s D.C. office, on K Street, is more vivid than his reporting on developments at corporate headquarters in Irving, Texas, or on the company’s dauntingly complex finances and technological, engineering, and geological-sciences efforts. For instance, he devotes sections of two chapters to recounting ExxonMobil’s attempts to sway “informed influentials”—representatives of nongovernmental organizations, D.C. policy wonks, and the like—less, it seems, for the intrinsic importance of these events than for the fact that he had ready access to some of the participants and is engaged with the matters discussed. Coll reveals his lack of engagement with what ultimately makes ExxonMobil tick when he casually comments that Americans fill up their cars twice a week. Would that this were true, from the corporation’s point of view, since that would be a rate nearly double the national average.