This article examines the relationship between academic specialization and student exposure to a range of academic domains of knowledge. It uses a concentration measure--the Herfindahl-Hirschman Index--to investigate whether students who choose single majors or double major are more or less concentrated in nine domains of knowledge most postsecondary institutions consider to be the intellectual core of a liberal arts general education. The results, based on an analysis of 240 undergraduate transcripts, indicate that--relative to single majoring--choosing similar majors (hyperspecialization) significantly concentrates student learning and choosing very different majors (hypospecialization) leads to more breadth.