The top reason the dropouts gave for leaving college was that it was just too hard to support themselves and go to school at the same time. Balancing work and school was a bigger barrier than finding money for tuition, they said. In fact, more than a third of the dropouts said that even if they got a grant that covered their books and tuition, it would be hard to go back to school, given their work and family commitments.

At a news conference Wednesday announcing the report, underwritten by the Bill and Melinda Gates Foundation, Frankie Barria, a 24-year-old former student from New York City, described the stops and starts of his educational journey.

“When I started college, I was living on my own at age 19,” Mr. Barria said. “My mom had left. Usually the bird leaves the nest, but in my case, the nest left the bird.”

Mr. Barria first enrolled at City College, but found it “unbelievably hard” to do well in school and maintain his job, so he left school. Later, he completed a semester at Kingsborough Community College, but stopped when his job became too demanding. Eventually, he enrolled at Medgar Evers College, but did not finish even one semester.

“Having a roof over my head and food to eat was more important,” he said.

Asked to rate 12 possible changes, the dropouts’ most popular solutions were allowing part-time students to qualify for financial aid, offering more courses on weekends and evenings, cutting costs and providing child care. The least popular were putting more classes online and making the college application process easier.

Hilary Pennington, a Gates Foundation education official, said two big factors associated with degree completion were going straight to college after high school and enrolling full time. But, Ms. Pennington added, colleges need to be more accountable for making sure their students graduate.

“If you try to leave a cellphone system, they almost won’t let you leave, and I just wonder if there’s something we need to think about in higher education,” she said. “We need a system where, if someone is struggling, if professors notice that somebody is missing a lot of classes, if someone doesn’t early register, they immediately go to student-life services, and someone reaches out.”