Castillo's research focuses on K-12 school choice and integration policies and their possibilities for, and limitations to, advancing racially equitable and democratic public education. Overarching themes in Castillo's writings include how school choice and integration policies affect poor students and students of color, with a focus on diverse Asian American students.
Investigates 10 Asian American parents in metropolitan Hartford, Connecticut; and the motivations underpinning their decisions to choose magnet schools for their children. Finds that parents emphasized “diversity” over “desegregation” in explaining their magnet school choices and discussed race in complex ways.
Examines how New York City activists conceptualized educational equity during the pandemic. Integration activists emphasized school integration for democratic equality; and meritocratic activists prioritized retaining the existing stratified system mainly to foster social mobility and social efficiency.