"increase enrolment" is correct and usable in written English.
You can use it anytime you want to discuss an increase in the number of people who have enrolled in something, such as a college or training program. For example, "The new scholarship program is helping to increase enrolment in the college."
One health training institution principal said, "Because of MMAM, we must increase enrolment but have no increase in funds for enrolling more students.
However, MDG2 will not be achieved despite the efforts to increase enrolment and improve quality.
Sightsavers' inclusive education programme aims to increase enrolment of blind and low-vision children in Uganda by 25% by 2016.
The government is pushing to increase enrolment to 30% of the age group by the end of this decade.
First, if universities are to create centres of excellence they will need greater freedom: for example, to recruit their staff, to set up experimental links with research bodies or to increase enrolment fees.
Once you imagine educating a thousand people in a single class, it becomes clear that open courses, even in their nascent state, will be able to raise quality and improve certification faster than traditional institutions can lower cost or increase enrolment.
Selective universities have moved swiftly to increase enrolments and income from tuition fees, with Ucas figures showing that they increased acceptances by 4% this year compared with just 1% for institutions with lower entry requirements.
Unless substantial financial resources are provided, there is a limited capacity to increase enrolments in nursing schools.
However, the programme has failed to keep pace with increasing enrolment and rapidly rising college tuitions.
Kenya has also abolished fees for secondary schools, increasing enrolment from 1.2 million in 2007 to 1.4 million in 2008.
According to the research of Fernando Yitzack Pavon, Improving Educational Quality in Honduras, decentralisation programs are a key strategy to increasing enrolment, strengthening community participation and improving efficiency.
