Traditionally colleges have relied on standalone non-credit-bearing developmental education (DE) to support students academically and ensure readiness for college-level courses. As emerging evidence has raised concerns about the effectiveness of DE courses, colleges and states have been experimenting with approaches that place students into credit-bearing coursework more quickly. To better understand which types of students might be most likely to benefit from being placed into college-level math coursework, this study examines heterogeneity in the causal effects of placement into college-level courses using a regression discontinuity design and administrative data from the state of Texas. We focus on student characteristics that are related to academic preparation or might signal a student's likelihood of success or need for additional support and might therefore be factors considered for placement into college-level courses under "holistic advising" or "multiple measures" initiatives. We find heterogeneity in outcomes for many of the measures we examined. Students who declared an academic major designation, had bachelor's degree aspirations, tested below college readiness on multiple subjects, were designated as Limited English Proficiency (LEP), and/or were economically disadvantaged status were more likely to benefit from placement into college-level math. Part-time enrollment or being over the age of 21 were associated with reduced benefits from placement into college-level math. We do not find any heterogeneity in outcomes for our high school achievement measure, three or more years of math taken in high school. [For the corresponding grantee submission, see ED613729.]