Biographical oral history interview. Traces Tremain's career through undergrad and graduate school. Discussion of his work with Jeremiah Ostriker at Princeton, interest in theory and dynamical modeling, and reception of dark matter theories as well as role of Vera Rubin. Contrasts astronomy in U.S. versus Canada. Post graduate work at Caltech and Cambridge. Time at MIT. Discussion of large-scale collaboration in NUKERS project. Covers his participation in three decadeal surveys for astronomy. Return to Princeton and tenure as department chair. Concludes with broad set of questions and discussion about major changes in astronomy, marriage of physics and astronomy, importance of theories about dark matter and dark energy.