Correction: A previous version of this post incorrectly reported that social workers are among non-instructional personnel being cut next year. Though social worker positions may be reduced at some schools, the overall number of social workers across the system is slated to increase, officials said.

Some D.C. parents, teachers and activists are warning that their schools stand to lose key staff and programs next year despite a promised 2 percent increase in per-pupil funding.

At Maury Elementary on Capitol Hill, for example, enrollment is projected to grow by 18 students to 330 next fall. But according to initial 2014 budget allocations released late last week, several full-time positions would shrink to part-time — including the librarian, the art and music teachers, business manager, social worker and psychologist.

In addition, the school’s after-care program appears to be slated for elimination.

Meanwhile, under the current budget, the school is required to add new positions — such as a part-time foreign language teacher — that are not key priorities, according to parents, who organized a letter-writing campaign in protest.

The changes will quash the momentum that Maury has built in recent years, they argued.

“This proposed budget threatens to undermine the community’s support for our schools and our support for your leadership,” wrote Amy Weedon, Maury’s PTA president, in a letter to Chancellor Kaya Henderson.

The chancellor replied to several parents that her staff is working with the principal to figure out how to best support the school. School system spokeswoman Melissa Salmanowitz emphasized that this is just beginning of what will be a months-long process to finalize the budget.

The changes come as the chancellor takes a more prescriptive approach to budgeting, giving principals less latitude in spending and scheduling decisions than they’ve had in the past.

That approach is meant to funnel more money into the classroom and to ensure equitable offerings at schools across the city, according to school system officials and the 2014 budget development guide.

“DCPS has set ambitious goals that require dramatic gains. To get there, we’ve made a commitment to our schools for the upcoming school year by making an unprecedented investment in the classroom,” Salmanowitz wrote in an e-mail.

“At this point, we’ve given our schools their initial funding allocations, which is the starting-off point and the first steps. Schools are working with their school communities to determine a budget and staffing plan that best meets their unique school needs. Budgets are still very much a work in progress.”

One key change: The school system is reducing some non-instructional staff, including clerks. The District employs far more such personnel than other similar school systems, according to a consultant for the system.

Another key change: Schools with 300 students or more are currently eligible for full-time librarians. Now the threshold is rising to 400 students. In addition, some schools like Maury, previously accustomed to full-time art and music teachers, may now have to cut into those programs to provide required foreign-language classes.

But other schools, including those that previously directed their art and music funds elsewhere, may see gains. C.W. Harris Elementary, for example, is currently budgeted for zero music teacher or librarian, a part-time art teacher and a full-time physical education teacher; next year, the school has a half-time librarian and three positions to split among P.E., art, music and world language.

Advocates for middle and high schools raised concerns Tuesday night about large class sizes and too few opportunities for electives at a sparsely attended hearing on school budgets held by Mayor Vincent C. Gray.

Though individual schools are wrestling with their budgets now, the chancellor has yet to present a comprehensive view of next year’s spending. That budget won’t be finalized and transmitted to the D.C. Council until March 28.

Public hearings are scheduled in March and April.