THE PROPOSAL by Mayor Muriel E. Bowser (D) to allow charter schools to give an edge to children who live nearby has several caveats. Only students who live within a half-mile of a charter school and whose in-boundary traditional public school is more than a half-mile away would be eligible for the preference. No charter school would be forced to set aside seats; it would be completely optional. But even with those limitations, a neighborhood preference has implications for the city’s thriving charter school community that must be thoroughly studied — and understood — before a final decision is made.

Saying she wants to “make it easier for more of our students to enroll in charter schools that are within walking distance of their home,” Ms. Bowser on Monday unveiled a new “walkability preference” that could affect an estimated 10,000 elementary school students. D.C. law currently gives children a guaranteed seat in traditional neighborhood schools but admission to charters, particularly the top-tier schools, is often decided by lottery. The change, which requires approval by the D.C. Council, would take effect in the 2018-2019 school year.

The question of access has long been a hot button for debate in a city where about half of the 90,000 public school students are enrolled in charters. Ms. Bowser campaigned on this issue, and her empathy for parents of children who don’t have the advantage of a school that is close by or that provides an education as good as a nearby charter is understandable. Children who walk to a school where they learn with the neighbors they play with clearly have an advantage.

But there are ramifications to a neighborhood preference that need to be thought through. Most significant is whether a move to a neighborhood preference would lock in neighborhood patterns of segregation that would keep students most in need out of high-quality charter schools. A task force that looked at the issue in 2012 concluded that if neighborhood preferences were mandated for charter schools, children in Ward 7 and Ward 8 would be most hard hit by losing access to high-performing charters elsewhere in the city. WAMU’s Martin Austermuhle reported that Council member David Grosso (I-At Large), who chairs the education committee, is concerned the plan “could spur some parents to strategically buy homes near schools that would qualify for the preference,” undermining the value of charter schools — that they are not linked to Zip code.

It will be critical that the council undertake a thorough review and, in particular, hear from the D.C. Public Charter School Board. It also is important that officials not lose sight of the larger need of ensuring there are more high-quality education seats in the city. Welcome steps in the right direction were Ms. Bowser’s plans, also announced Monday, to give charters an increase in their allotment for school facilities and to make additional city buildings available to them.