Eric David Harris was born in Wichita, Kansas. The Harris family relocated often, as Eric's father, Wayne Harris, was a U.S. Air Force transport pilot. His mother, Katherine Ann Poole, was a homemaker. The family moved from Plattsburgh, New York, to Littleton, Colorado, in July 1993, when Wayne Harris retired from military service. He met Dylan Klebold while enrolled at Ken Caryl Middle School.
Dylan Bennet Klebold was born in Lakewood, Colorado, to Thomas and Susan Klebold (née Yassenoff). His parents attended a Lutheran church with their children, and Dylan and his older brother, Byron, attended confirmation classes in accordance with Lutheran tradition. At home, the family also observed some rituals in keeping with Klebold's maternal grandfather's Jewish heritage. Klebold attended Normandy Elementary in Littleton, Colorado for the first two grades before transferring to Governor's Ranch Elementary and became part of the CHIPS ("Challenging High Intellectual Potential Students") program. He found the transition to Ken Caryl Middle School difficult, where he befriended Eric Harris, who was new in town.