On Wednesday, D.C. schools Chancellor Michelle Rhee--once featured on the cover of Time magazine holding a broom, alongside the words "How to Fix America's Schools"--announced she would step down after a little more than three tempestuous years. Her announcement, expected since the primary defeat of her patron, Mayor Adrian Fenty, drew the sorts of accolades and brickbats that have characterized her tenure.

There's been much attention paid, deservedly, to Rhee's willingness to remove ineffective educators and negoatiate a new contract with the Washington Teachers Union that dramatically altered the shape of teacher compensation and tenure. Drawing less notice is her success cleaning up a system that was profoundly dysfunctional in nearly every way.

On her watch, D.C. public schools pioneered a cutting-edge teacher evaluation system, fixed a broken personnel system, overhauled textbook requisition and distribution, shuttered dilapidated and half-empty schools, addressed a massive backlog in its special needs caseload, slimmed a bloated central office and built a respected data and research operation.

There are three key lessons for reformers. First, mayoral control has limits. In recent years, many reformers have suggested that mayoral control is the be-all, end-all of accountability. The problem is that this advice is derived largely from the experiences of two exceptional mayors: Richard Daley in Chicago and Michael Bloomberg in New York.

Elsewhere, ugly politics still rears its head. Fenty was upended by a challenger who attacked him as high-handed and inattentive to community sensibilities. Rhee's efforts were hardly the sole reason for this, but Fenty's staunch support for her tough-minded measures became a primary point of contention. With Fenty out, the bottom fell out for Rhee.

Second, it's a big mistake to imagine that things would have been different in D.C. if only Rhee or Fenty had been "nicer." Education reformers love to talk about the importance of reaching consensus.

If the goal is to improve a reasonably performing organization, that's a viable strategy. Rhee was hired to clean up a disaster zone. You can't do that without bruising feelings--in communities where schools are being closed, among fired principals and central staff and in the teachers union. When it comes to troubled systems, even a thousand get-to-know-me sessions and stakeholder roundtables won't suffice.

Rhee can testify to this, because she held scores of community conversations in 2007-08 when pursuing desperately needed school closings--only to be slammed for inadequate efforts to garner input or secure community buy-in.

Third, even "action hero" reformers can't do it all by themselves. Rhee and Fenty operated on the premise that, if they could deliver impressive academic results in the first couple of years, their critics would melt away. Well, Rhee delivered impressive results, and the criticism and conflict only built--to the point where Rhee and Fenty were drawing support from less than 30% of the local African-American community.

Transforming dysfunctional systems is inevitably disruptive. It provokes discomfort, even when you can demonstrate clear progress. Even among parents of kids at failing schools, who welcome the thrust of the reforms. To win the debate, would-be reformers need credible local allies who are consistently explaining why the harsh medicine is necessary.

Rhee's experience proves it's not just about mayors, manners or academic momentum. Turning troubled urban school systems around requires community cover and local political muscle. That's where cheering reformers failed to deliver for Fenty and Rhee.

Frederick M. Hess is a resident scholar and the director of education policy studies at AEI.

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