Declared the “worst schools in the nation” by Education Secretary William Bennett in 1987, Chicago today is the fastest-improving district in the country, according to Stanford professor Sean Reardon, with students gaining a remarkable six years of learning in five years.

It’s not just test scores, says Elaine Allensworth of the UChicago Consortium on School Research. Student attendance is up, high schools are offering more rigorous courses, and high school graduation and college enrollment rates are rising.

So what’s driving Chicago’s success?

There is no shortage of theories, from greater school choice and accountability to unsexy stuff like professional development and aligned curriculum. Others credit principal autonomy, demographic shifts, mayoral control, expanded preschool, and better use of data. In Chicago’s case, however, there are some clear lessons to be learned from 30 years of reform, especially around strong school leadership, great teaching, data, and transparency.

Much of the credit for rising graduation rates goes to the development of a freshmen-on-track metric devised by the consortium and targeted interventions from local organizations like the Network for College Success. It may just be that after 30 years of reform and experimentation, Chicago has finally hit a tipping point and a culture of continuous improvement has set in.

If there are any concrete takeaways from the Chicago experience, they are:

  • Good data presented honestly and independently really matters.
  • There are no good schools without good principals.
  • The politics of mayoral control cannot be discounted.

Read the full article about education reform by Peter Cunningham at The 74.