Charter schools are making their presence known in American cities. After more than a decade of steady growth, 10 percent of urban public school students are now enrolled in charters, where research shows the typical student benefitting more than at district schools.

With success comes criticism, however, and charter schools have been challenged by groups claiming they pass over disadvantaged students. In a new study, I demonstrate that a straightforward change to the application and enrollment process could ensure that charters reach the students most in need.

It’s well known that charters serve significantly smaller proportions of students who are eligible for free or reduced-price lunch, speak English as a second language, or have a disability than do surrounding district schools. Yet both critics and supporters claim to want charters to serve more disadvantaged students.

While some— such as former Secretary of State Hillary Clinton — argue charters are pushing such students out the door, studies from myself, researchers from Vanderbilt and Indiana University, as well as the Independent Budget Office find them to be less likely to leave charters than they are district schools.

The truth is far less insidious: Students in these disadvantaged groups are underrepresented in charters primarily because they are less likely than other students to apply for admission.

In a study last year, I demonstrated that the difference in the percentage of students classified as English language learners in New York City charter and district schools is nearly entirely explained by such students being unlikely to apply to attend a charter school in transition grades. For instance, the gap in English language learner enrollments in New York City is largest in kindergarten where 20.8 percent of students entering district schools were so classified, compared to only 7.6 percent of students entering the city’s charter schools.

In most cities, each charter school has its own application process separate from that used to enroll in a district school. Parents with more information, resources and bureaucratic acumen more easily maneuver through these systems. According to a recent survey conducted by the Center on Reinventing Public Education, parents with less education and those with children who have disabilities were more likely to report difficulty navigating deadlines, multiple applications and sorting out their child’s eligibility for schools.

If the problem is application, not retention, policies should focus on encouraging access. Policymakers pursing the goal of more diverse enrollment should focus on improving the unnecessarily burdensome charter application process.

Some cities have recently scrapped the typical multiple application “system” for a centralized enrollment process — called “common enrollment” — that allows families to apply to multiple charter or district schools. Each year, parents submit a single municipal form with an ordered list of schools they would like their child to attend. A central system then runs a lottery to assign students to schools by an algorithm intended to produce efficient and equitable matches. Denver; New Orleans; Newark, N.J.; and Washington have all adopted such common enrollment systems that incorporate charter schools.

Adopting a uniform application reduces the burden of applying to a charter school. By combining the process for applying to charter schools and district schools, common enrollment systems might also reduce preconceived notions that a charter is an inappropriate fit for their child by making the charter appear as just another choice among many.

Additionally, common enrollment systems require no direct contact between parents and schools and thus could circumvent attempts by charters to discourage parents of disadvantaged students from applying, if that practice exists as charter critics often allege.

Survey evidence from the Center on Reinventing Public Education shows that Denver’s parents, particularly those with lower education levels, found the common enrollment system much more accessible and less confusing than former systems.

My most recent study finds evidence Denver’s adoption of a common enrollment system increased the number of minority, free or reduced-price lunch, and ESL students entering the city’s charter elementary schools. (Students with disabilities did not participate fully in the enrollment system during the years evaluated.) The surge nearly eliminated the difference between the percentage of ESL and bilingual students entering charter and district schools, and it cut the gap for free or reduced-lunch students nearly in half.

Several additional cities are reportedly considering adopting common enrollment systems that incorporate charter schools, including Boston, Detroit, Chicago, Oakland, and Indianapolis. In addition, expanding the already operating common enrollment systems in New York City to all grades and to include charter schools could increase access for disadvantaged students to the city’s high performing charter sector.

Common enrollment systems could offer an opportunity to increase the access that such students have to charter schools at a minimal cost to either the charter or district sector. Charter sectors in these and other cities should embrace common enrollment systems as a way to make it easier for all types of students to apply.