This paper provides an econometric analysis of the matriculation decisions made by students accepted to Williams College, one of the nation's most highly selective colleges and universities. Using data for the Williams classes of 2008 through 2012 to estimate a yield model, we find that--conditional on the student applying to and being accepted by Williams--applicant quality as measured by standardized tests, high school GPA and the like, the net price a particular student faces (the sticker price minus institutional financial aid), the applicant's race and geographic origin, plus the student's artistic, athletic and academic interests, are strong predictors of whether or not the student will matriculate. (Contains 2 figures and 3 tables.)