It's not a surprise that Social Analysis 10, "Principles of Economics," taught by Baker Professor of Economics Martin Feldstein '61, leads this semester's list of Harvard's largest classes.

But last year's second-place finisher Literature and Arts B-51, "First Nights," dropped to fourth, with enrollment decreasing considerably over the past two years.

Up from 808 last year, 827 students are officially registered for Ec 10, the full-year course that perenially packs Sanders Theater.

Moral Reasoning 22, "Justice" comes in a close second with an enrollment of 789. With 437, Science B-29, "Human Behavorial Biology" is the third largest course on campus, according to the registrar's Web site.

The enrollment for "First Nights" has fallen from 722 two years ago to 670 last year, and now, only 427.

General Education 105, "The Literature of Social Reflection" attracted 377 students, making it the fifth most popular course.

Ec 10, "Justice" and "First Nights" are held in Sanders Theater, which has a capacity of 1,166.

Interest in Science B-29, more commonly known as "Sex," exceeded the capacity of its 500-seat Science Center B lecture hall. Instructors held a lottery to determine who was allowed to enroll. The course hadn't been lotteried for the past two years.