The City University of New York has chosen James B. Milliken, president of the University of Nebraska, as its next chancellor -- and in many ways the new job is likely to be an education for him.

He's leaving a system with 50,000 students and four campuses to run a system with 270,000 students and 24 campuses. But he does know our city. A 1983 graduate of New York University law school, he has worked as a Wall Street attorney and with the Legal Aid Society here.

Still, the task he faces at CUNY should daunt anyone.

Milliken was chosen in part for his strong record in bringing more low-income and minority students into the Nebraska system. He must do the same at CUNY -- without losing the tougher admissions standards imposed by his predecessor, Matthew Goldstein.

That's an immense mandate.

To keep New York's income gap from continuing to widen -- to keep the city's long tradition of upward mobility healthy -- Milliken must increase the enrollment of low-income and minority students at CUNY while continuing to build its academic standing.

He must build a university that can prepare all New Yorkers -- regardless of income or background -- for the knowledge-based economy that awaits them.

The reassuring news is that graduation rates in the city's public high schools have risen in recent years -- to around 65 percent. The alarming news is that only 38 percent of those grads are adequately prepared for college or careers, according to the State Education Department.

The vast majority of CUNY students come from the city's school system. So Chancellor Milliken must work as a team with Mayor Bill de Blasio and Schools Chancellor Carmen Fariña to better prepare students for college.

He must also keep the price right. The system's 11 senior colleges cost about $5,730 a year for in-state students. In an age of stratospheric tuitions, that's a great bargain.

Now we need more grads who can make the most of it.