David Levin has a message for principals who want to turn failing schools into high-quality centers of learning: Two plus two equals five.

That, at any rate, is what Levin, a co-founder of the KIPP (Knowledge Is Power Program) Academies, told an audience at a recent education conference in Philadelphia. In short, the way to become a successful principal is put aside the conventional wisdom on how schools operate and make your own rules.

Looking at KIPP's success, it's clear that Levin knows a thing or two about how to promote student achievement. He operates a KIPP school in the Bronx borough of New York, and for three straight years, it's been the highest-performing area middle school on standardized reading and math tests - despite having a student population drawn almost entirely from low-income families.

KIPP's success in the Bronx school is no fluke. The Texas Education Agency has recognized the KIPP Academy in Houston as an "exemplary school" every year since it opened in 1994, and it's the highest performing of the 38 middle schools in the Houston Independent School District. Every student in the class of 2003 graduated from high school and was accepted to at least one college.

There's also the remarkable performance logged by the KIPP school in the District of Columbia. "The KIPP seventh-graders . . . jumped from 34.1 to 52 on the 99-point normal curve equivalent scale in reading in just two years, an almost unheard of improvement for children growing up in underserved, non-college families," wrote Washington Post reporter Jay Mathews. "The math increase was even more impressive, from 41 to 72 in those two years."

So what is KIPP doing right? A former colleague of ours here at The Heritage Foundation, Samuel Casey Carter, has some answers. He examined the KIPP Academies in Houston and New York, along with 19 similar schools, in the book "No Excuses: Lessons from 21 High-Performing, High-Poverty Schools."

Carter wanted to give these schools the recognition they deserve, of course, but his goal was also to identify what it is that makes them and their principals successful.

Carter listed seven defining traits of a No Excuses school:

• The principal is free from bureaucratic meddling.
• The school sets measurable goals.
• "Master" teachers assume leadership roles among the faculty. Regular testing leads to continuous achievement.
• Student achievement helps maintain discipline.
• The school sets up contracts with parents to "make the home the center of learning." Teachers and students work longer than the traditional school day.

KIPP, which has been profiled everywhere from "60 Minutes" and MSNBC to Newsweek and The New York Times, is especially notable because of its extended schedule. They have longer school days (7 a.m. to 5 p.m.), hold classes two Saturdays each month and have a longer school year.

It's the first characteristic identified by Carter, though, that really separates KIPP Academies and other no-excuses schools from those that don't see student achievement: a strong principal. "Effective principals decide how to spend their money, whom to hire and what to teach," Carter says. "Effective principals either are given their freedom or take it for themselves."

Good principals will use their freedom to implement some of the other tactics that have made students in no-excuses schools successful, such as setting measurable goals and testing students regularly.

Principal Nancy Ichinga is an excellent example. This former head of what is now Bennett-Kew Elementary School inherited a student population where 95% of the children were illiterate. Four years later, her students were scoring in California's 50th percentile, and the school would go on to become one of the best public schools in Los Angeles. Ichinga's leadership in implementing a new curriculum and testing students frequently to measure their progress was central to changing Bennett-Kew's course.

Recently, another principal with close ties to Heritage's no-excuses program was honored in a ceremony in the White House Rose Garden for her success - which came by way of the same methods identified in the book. Linda E. Reksten is principal of Disney Elementary School in Burbank, Calif., and she got Disney dropped from her state's list of underperforming schools with what President Bush called a "rigorous" testing program.

Former Heritage Foundation scholar Megan Farnsworth, who led the no-excuses campaign at the Foundation for several years, helped Reksten accomplish this by serving as Disney's curriculum specialist before joining Heritage - which meant co-designing the new curriculum and the rigorous testing strategy that boosted student achievement.

The result: Over the past four years, Disney students have jumped 18 percentile points on reading assessments and 27 points on math. And this from a student body where nearly half do not use English as a first language and two-thirds are from low-income families.

The seven traits identified by Carter describe Disney Elementary, as well as KIPP Houston and Bennett-Kew. Farnsworth saw these methods in action and knows they work.

"Holding students to high academic standards without regular testing is like expecting high returns from a business without being able to check its quarterly earnings reports," she says. "Anything less just doesn't add up."

And as every good principal will find, sometimes two plus two does add up to five.

Jonathan Butcher is a researcher in domestic policy and Krista Kafer is an education policy analyst at The Heritage Foundation.