After 20 years as Yale’s leader, University President Richard Levin will step down from his post at the end of the 2012-’13 school year, he announced in a Thursday morning email to the Yale community.

In his email, Levin said he recognized that it is a “natural time for transition” after being at the University for more than 40 years, first as a graduate student and later as an economics professor.

“These years have been more rewarding and fulfilling than I ever could have imagined,” he wrote in his email.

Levin said he planned to take a sabbatical after leaving his post and complete a book reflecting on higher education and economic policy. He did not name a successor. Read the full text of the email below:

I write to inform you that I will step down from my position as President of the University at the end of the current academic year, my twentieth year of service.

From the day Jane and I entered graduate school in 1970, Yale has been our life. Since I joined the faculty in 1974, my efforts – as teacher, scholar, and President – have been rewarded in superabundance. As President, I have had the strong and enabling support of devoted faculty, staff, students, alumni, trustees, and friends, but as my twentieth anniversary approaches, I recognize that this is a natural time for a transition. We stand between the realization of many important institutional goals and another round of major initiatives. We have successfully completed the Yale Tomorrow campaign, renovated all twelve residential colleges, reduced our budget in the wake of the financial crisis, secured the funding to construct the new School of Management facility, achieved critical mass on the West Campus, and ensured the successful launch of Yale-NUS College by recruiting outstanding leadership and the first cohort of faculty, and breaking ground on a new campus. Before us lie decisions about when to proceed with such projects as constructing the Yale Biology Building, facilities for science teaching, a new home for the School of Drama, and two new residential colleges, as well as renovating the Hall of Graduate Studies and Hendrie Hall.

It is a source of great satisfaction to leave Yale in much stronger condition – academically, physically, and financially – than it was when I began in 1993. Our faculty is stronger than ever, and our deans and directors all have clear and ambitious agendas that will keep the University moving forward. Our partnership with the city of New Haven has led to great improvement in the condition of our downtown and surrounding neighborhoods. We have transformed relations with our labor unions. And we have become a truly global university – providing international experiences to the great majority of our students, supporting hundreds of faculty collaborations throughout the world, and, influencing the development of law, the effectiveness of health care delivery, and the course of global higher education.

To the faculty and staff who contribute daily to the work of the University, to the students who give it meaning, and to the alumni and friends who provide generous support, I offer my profound thanks. These years have been more rewarding and fulfilling than I ever could have imagined. My words on accepting my appointment as President are as true today as they were on April 15, 1993: “The greatness of this institution humbles me.” I am deeply grateful for having had the opportunity to serve Yale.

I look forward to a sabbatical next year, when at last I will have the time to complete a book of reflections on higher education and economic policy.