"I think it has more to do with the strong economy," Walser says. "[Private school enrollments] have gone up across the board."

In fact, parents determined to keep their children in public school may actually find Cambridge a better alternative than many nearby districts, Walser says.

"People are moving to Cambridge for our public school system," she says. "We have small schools, and we also have very favorable student-to-teacher ratios."

Choice or Chance?

The system of school choice, a distinguishing feature of Cambridge public schools, both attracts and deters potential students.

Under the current system, parents submit their top three choices of programs--e.g., traditional programs, bilingual programs, arts-focused programs--for their children. Children are given priority in the two schools nearest their home, each of which may house more than one program.

That's complicated by district caps for the percentage of white, black and "other" students in each school. Particularly in racially imbalanced neighborhoods, students may be barred from attending schools of their choosing or even schools near their homes because of these caps.

"In many cases this artificially depresses our enrollment, if a certain race of child wants to get into a school and it's full," Walser says.