Walk up Mass Ave. and you might hear a different language on every block. More than a quarter of Boston’s residents are foreign born, and nearly half of all kids in Boston have at least one foreign-born parent, according to city figures.

But learning English isn’t so easy. More than half of those in need of English-language classes end up on wait lists.

About 3,400 adults are enrolled in English to Speakers of Other Languages (ESOL) classes in Boston, but another 4,000 are waitlisted, according to Alejandra St. Guillen, director of the city’s Office of New Bostonians. That’s only for state-funded programs in the city; but the pattern is the same for private courses.

“Boston has always been a city of immigrants,” St. Guillen said. “You can’t find a place in Boston that doesn’t have a growing immigrant population.”

On March 26, Boston Public School’s English-language learners will be among those who will visit the Massachusetts State House to demand more funding for Adult Basic Education programs, which includes ESOL classes.

“The problem exists because there’s been a defunding and divestment from the state,” said City Councilor Ayanna Pressley. “Our state partners need to step up and make a greater investment. We’re struggling.”

St. Guillen said that funding for ESOL classes comes from the school system, federal funds, and state and private grants. It costs Boston Public Schools about $500,000 to teach 200 ESOL students, or about $2,500 for each student.]