Note: This post has been updated to correct statistical errors.

A new report finds evidence of a new majority on college campuses: part-time and “non-traditional” students.

Two-fifths of today’s college students attend part time, and three-quarters live off campus, juggling classes along with work and family responsibilities, according to a new report from the nonprofit Complete College America. Only one quarter attend residential colleges as full-time students supported by their parents, the customary vision of college embraced by the suburban middle class.

The federal government doesn’t track part-time students, the report says, which means official measurements of success or failure in higher education don’t take them into account. The new report “Time is the Enemy” works around this problem by gathering data direct from 33 states.

Outcomes for part-time students are starkly worse than for their full-time counterparts. The completion rate for part-time students seeking a bachelor’s degree is 24 percent in the states surveyed, even when students are given eight full years to finish. The corresponding completion rate for full-time students is 61 percent. Among two-year community college students, the completion rate is 19 percent for full-time students and just 8 percent for part-time students, and that’s allowing four years to finish.

To put those numbers in context, consider the consequences if a large public school district were to announce that its graduation rate was 24 percent. There’s growing talk in higher education of collegiate “dropout factories,” schools whose remarkably low completion rates are seldom brought to light.

Completion rates are lower still among under-represented minorities. The bachelor’s completion rate is 17 percent for Hispanics who attend part-time, 15 percent for African Americans, even after allowing eight years to finish.

Part of the problem is that students are wasting their time amassing more credits than they need to graduate. This is partly a matter of poor or nonexistent advising, and partly a consequence of students attending multiple schools and those schools refusing to transfer credits.

The average community college student who earns an associate degree completes 85.5 credits, while the degree requires only 60. Bachelor’s candidates average 136.5 credits for a degree that requires 120.

Part-time students take five years, on average, to complete a two-year associate degree. They take 5.6 years to finish a four-year B.A.

Complete College America is a new nonprofit founded solely to work toward higher completion rates and backed by a star-studded cast of educational foundations as well as the nation’s governors.

The report offers a long list of fairly specific fixes. A sampling:

• More flexible scheduling for students, with classes offered year-round and in shorter terms.

• Formal “completion plans” for every student, updated annually.

• A common core curriculum of general-education courses that are consistent and transferable from school to school.

• Cap credit hours at 120 for a bachelor and 60 for an associate degree.

The report includes data for Maryland and Virginia, which were both among the 33 participant states.

Maryland reports a graduation rate of 18 percent for full-time students seeking associate degrees, and a strikingly low 6 percent for part-time students, given four years to complete.

Virginia reports a graduation rate of 20 percent for full-time A.A. students and 9 percent for part-timers.

Maryland reports a graduation rate of 67 percent for full-time students and 18 percent for part-time students seeking bachelor degrees. Virginia’s corresponding rates are 73 percent and 29 percent.