This mixed-methods study used open-response survey data, focus groups, and an experimental simulation to explore how 311 admissions officers defined and used concepts of holistic review in selective college admissions. We found that 3 distinct definitions of holistic review predominate in the field: whole file, whole person, and whole context. We explored these concepts qualitatively and used the coded data to predict decision making in an experimental simulation. We found that admissions officers with a "whole context" view of holistic review were disproportionately likely to admit a low socioeconomic-status applicant in our simulation. Inconsistent definitions of a core admissions concept make it more difficult for the public to comprehend the "black box" of college admissions, and a more consistently contextualized view of holistic review may also have real-world implications for the representation of low-income students at selective colleges.