Two years ago, only 150 students attended Holabird Elementary, then a K-5 school in the southeastern corner of this city. Competition from charters and from regular public schools in nearby Baltimore County had drained families from Holabird, a chronic underperformer. So when Andres A. Alonso, the chief executive officer of the Baltimore city schools, began last year to allocate money to schools based on their students' needs, Holabird stood to be hit hard. Achievement had started to rise, but its small roster put the school at risk of losing six teachers unless more students enrolled. Principal Lindsay Krey, about to start her second year as the leader of the school, decided to knock on some doors. The door-knocking campaign worked: Fifty new students enrolled for the 2008-09 school year, sparing Holabird from budget cuts. And it gave Mr. Alonso a powerful example of how his "fair student funding" model could inspire hustle and creativity from principals, who under the new model are in control of most of their budgets. Fair student funding is just one piece of a multipronged strategy that Mr. Alonso, a Harvard University-trained lawyer who taught special education in Newark, N.J., has introduced since becoming Baltimore's schools chief in 2007. Given broad latitude by the appointed school board members who hired him, Mr. Alonso has replaced roughly 40 percent of the city's principals, eliminated more than 450 positions in the central office, shut down or overhauled failing schools, and opened a variety of schools designed to serve children at risk of dropping out. Three years after Maryland's top education official threatened to take over or close several low-performing Baltimore schools, Mr. Alonso presides over an 83,000-student district that has moved out of the bottom academically and gained momentum around raising student achievement.