A wide range of actors are taking notice that low-income students constitute less than 5 percent of the enrollment at the U.S most selective institutions, a percentage that, despite a great deal of effort and policy reform, has remained virtually unchanged for decades. Yet in the past two years, only 11 percent of selective colleges have increased their focus on socioeconomic diversity. Meanwhile, students at the upper-end of the income spectrum come from families whose wealth has accelerated during that time, leading to greater disparities on campus between the haves and have-nots. In this context, the author reviews some of the institutional impediments— “supply-side factors”—to an equitable system of selective college admissions. He explores what we know about the crucial factors that shape a student’s holistic review beyond the grades and standardized test scores used in most of the existing literature on undermatch. He also examines what we know about how the drive for revenue and prestige determine decision-making, and result in intense pressures for enrollment managers to produce results that meet institutional targets. Finally, the author discusses how two important factors—replacement and scale—are likely to influence any future reduction in undermatching behavior.