In this interview, David Zierler, Oral Historian for AIP, interviews Gene Beier, professor of physics at the University of Pennsylvania. Beier recounts his childhood in Illinois and his undergraduate experience at Stanford University, where he became close with Sid Drell, who encouraged him to pursue his graduate degree at the University of Illinois. Beier describes his work at the University of Illinois with his advisor Louis Koester, and his research at Brookhaven and Argonne Labs where he was involved in the search for a lepton heavier than the muon, but with a smaller mass than the K meson mass. Beier explains his decision to join the faculty of the University of Pennsylvania and he describes collaborations with some of his graduate students, his work at Fermilab, and the impact of quantum chromodynamics on his research. In the last portion of the interview, Beier explains the history of neutrino flux and his longstanding research on the atmospheric neutrino effect.