In this study, I exploit exogenous differences in institutional policies regarding the treatment of home equity in grant aid allocation to estimate a causal impact of institutional grant aid on college choice. Because institutional grant aid is typically not awarded randomly, the college-estimated home equity value serves as an instrumental variable from which the causal relationship between institutional grant aid and college choice is identified. An additional $1,000 in institutional grant aid awarded by the typical sampled college increases the probability that the typical accepted student will choose that college by 1.66 percentage points. I also find that choice elasticity varies by student socioeconomic status, with the lowest income students nearly three times more sensitive to institutional grant aid than high-income students. (Contains 4 tables, 5 figures, and 6 notes.)