"From the moment students enter a school," President Obama said in his first major education address since taking office, "the most important factor in their success is not the color of their skin or the income of their parents; it's the person standing at the front of the classroom."

But too often, schools of education can't be counted on to provide the type of teachers that schools—especially those that serve more challenging populations—need. Many are afflicted by low admission standards and meaningless course work.

Beginning in 2003, the Boston Public Schools took matters into its own hands by starting the Boston Teacher Residency program. In BTR, new teachers spend a full year working with a mentor teacher four days a week in a classroom. At the same time, the teachers take courses specifically tailored to prepare them for Boston's public schools. During their second year, they earn a master's degree from the University of Massachusetts at Boston and receive licensure, both at no cost. In return, teachers commit to spending at least three years with the school system.

The extremely selective program—only about 13 percent of applicants are accepted—is going a long way toward achieving the goal of a highly qualified teaching corps. As of the fall of 2010, 296 teachers had graduated from the program and 75 more prospective Boston teachers were working their way through it.

As the requirement that teachers commit to three years with the school system suggests, retention is a critical part of the teacher-quality equation. When BTR began in 2003, 53 percent of new BPS teachers were leaving within three years. Since research shows that teachers become progressively more effective over their first three to five years, the losses came just as the teachers' value was rapidly increasing.

The monetary costs of high turnover are also dramatic. Depending on whether the departing teacher had one, two or three years of experience, the cost of replacing him or her ranged from about $10,000 to $27,000. All told, the annual tab for teacher replacement was more than $3 million.

Those dire statistics are a thing of the past among the BTR cohort, for whom the three-year retention rate now stands at 84 percent. The savings paid for a healthy chunk of the program's $4.5 million budget for fiscal 2011.

Now that BTR has achieved critical mass and dramatically improved teacher retention, the next step will be to measure the bottom line—its impact on student achievement. There are signs that the news will be good: In a survey of BPS principals and headmasters, 55 percent said BTR-prepared teachers were "significantly more effective" than other first-year teachers. It's no wonder that Edutopia magazine recently named BTR one of the "10 leading schools of education."

The Boston Teacher Residency Program was one of six finalists for the 2011 Innovations in American Government Award, given annually by the Ash Center for Democratic Governance and Innovation at the Harvard Kennedy School.