Over half of students at R1 public universities – and over three-quarters of students in lucrative majors like engineering and economics – earn college majors that impose GPA or application restrictions on which students are permitted to declare the major. A typical restriction prohibits students who earn lower than B or B- grades in the department’s introductory courses from declaring the major. Our prior work has shown that major restrictions differentially impact disadvantaged students and lead them toward lower-value college majors. This study investigates six potential efficiency benefits and costs of major restriction policies: e.g. whether restrictions differentially admit students with comparative advantages in the field, whether restrictions push low-GPA students into fields of study in which they are more likely to graduate, and whether restrictions increase college majors’ value to their remaining students. We find no evidence of efficiency benefits and substantial evidence of efficiency costs of major restriction policies relative to not implementing major restrictions.