Miller points to the state's new standardized testing system, the Massachusetts Comprehensive Assessment System (MCAS), as one factor that leads parents to favor private schools.

"There's a lot of creativity in the Cambridge schools that's being squashed because of the focus on testing," says Miller, who was formerly on the Haggerty School's school committee. "For parents who have the ability to move their children to private schools, this may be a factor."

But D'Alessandro responds that the district still encourages teachers to adapt the standardized curriculum into individualized, innovative lessons.

"Parents worry that we're going to teach the test, but we really aren't," she says.

Not Just a Cambridge Concern

Since the Massachusetts Department of Education does not assemble data distinguishing private and parochial enrollments from public enrollments, it's hard to say whether the Cambridge phenomenon of falling public and soaring private enrollments is unique.

School Committee candidate Nancy Walser, who spoke with admissions directors at Cambridge's private schools for her book on Cambridge schools, says private schools' new applicants are not just coming from Cambridge.

Thus, her guess is that it's not necessarily quality concerns causing Cambridge public schools to lose students.