Chinatown ESL is a public service program under the Chinatown Committee of Harvard's undergraduate service organization, the Phillips Brooks House Association. It is an English-as-a-Second-Language program serving the Chinese immigrant population of Greater Boston. The students range from newly immigrated working adults to senior citizens. The curriculum is divided among the most basic to highly proficient into five levels with two tutors teaching a class of five to fifteen students. Classes are held Saturday and Sunday for two hours, from 11AM to 1PM in classrooms on Harvard's campus.