Before 1974, general high schools in Korea were stratified by a selective admission system.
Starting from 1974, it was replaced by a leveling system in which students were randomly
assigned to a school within a district. This paper examines whether the quality of school ties
formed by senior graduates of the selective system affects contemporary outcomes of junior
graduates randomly assigned to the same school under the leveling system. The quality of
school ties does not strongly affect the average junior graduate’s outcomes. In contrast, it
benefits junior graduates who rank high in the outcome distribution.