It remains one of the mysteries of our political age: How did a Wall Street-spawned meltdown and the worst recession in decades spark a populist reaction against government? In the 1930s, the failure of a Republican administration and laissez-faire economics led to a leftward swing and the New Deal. In our time, the financial crisis seemed poised to catalyze a revived reformism. But mere months—weeks even—after President Obama’s swearing-in, angry Americans began gathering in living rooms and town halls and public parks to demand an end to government tyranny.

Who are they, and what do they want? In the nearly three years since the Tea Party’s efflorescence, political observers and the media have sought answers to those questions. A third question—what are they capable of?—has already been answered. Many liberals and political elites scoffed when the army of tricorn-wearing, teabag-toting protesters first appeared. A midterm election and a hijacked government later, the smirks are gone. The Tea Party, it turned out, is a real force, and its impact has been nothing less than seismic.

The last couple of years have seen a rush of volumes hoping to explain and exploit the phenomenon, their titles matching the movement’s heat: Boiling Mad, The Whites of Their Eyes, The Backlash, Give Us Liberty, Mad as Hell. Theda Skocpol and Vanessa Williamson’s The Tea Party and the Remaking of Republican Conservatism might seem a latecomer, but it is in its own way well timed, arriving in the midst of a presidential campaign. What does the Tea Party do now that it has had a taste of governing? And where does American democracy go from here?

As its comparatively bloodless title suggests, The Tea Party and the Remaking of Republican Conservatism eschews rhetoric in favor of rigor. Skocpol, an influential sociologist and political scholar at Harvard (and, full disclosure, a member of the editorial committee of the magazine where I work), and Williamson, a PhD student in government there, employ both qualitative and quantitative methods to give us a head-to-toe anatomy of the Tea Party movement. A systematic and disciplined analysis, it is the definitive study of the Tea Party to date.

Skocpol and Williamson see the Tea Party as neither solely a mass movement nor an Astroturf creation, arguing for something in between: a grassroots movement amplified by the right-wing media and supported by elite donors. To better understand their subjects, the authors went into the field, observing meetings and conducting phone and in-person interviews.

For too long, a credulous mainstream media depicted the Tea Party as an uprising of independents fed up with the dominant political parties. But as Skocpol and Williamson assert—and as other astute commentators have been saying all along—they’re not really new, and they’re hardly independent. Indeed, they’re little more than a hard-core faction within the Republican Party—the “most recent incarnation of American conservative populism.” Come election time, “Tea Partiers do not engage in swing voting in general elections,” they write. “[T]hey support the enemy of their main enemies: they vote for candidates that can displace Barack Obama and other Democrats.”

It’s all aimed at reducing the size of government—or is it? One Virginian voiced a typical, if debatable, sentiment: “The nation is broke. It is bankrupt.” But as others have noted, the Tea Party’s anti-government impulse, while no doubt deeply held, sounds more talking point than principle when you subject it to interrogation. The authors surprised some of their interviewees by asking if there was anything they liked about government. Forced to inspect the object of their hatred, Tea Partiers found things to applaud: national parks, health care for children through Medicaid, the grandeur of the nation’s capital.

And, of course, entitlements. In surveys, Tea Partiers support Social Security and Medicare, even going so far as to back tax hikes to keep the programs funded; an oft-quoted sign at a Tea Party rally warned potential meddlers to “keep the government’s hands off my Medicare.” Critics have pounced on such incoherence as evidence that the Tea Party position is driven by self-interest. As surveys have shown, Tea Partiers tend to be white, churchgoing, wealthier than the average American—and retired.