Interview with Stephen Fulling, Professor of Mathematics and of Physics and Astronomy at Texas A&M University. Fulling explains the history of why his primary academic department is math and how the field of general relativity became more directly relevant to observational cosmology in the 1960s and 1970s. He recounts his middle-class upbringing in Indiana and his dual interests in math and physics which he developed during his undergraduate years at Harvard. Fulling discusses his graduate work at Princeton, where Arthur Wightman supervised his research. He explains the contemporary controversy over the Casimir effect and his interest in the Minkowski vacuum, and he discusses his postdoctoral appointment at UW-Milwaukee. Fulling describes his work on Riemannian spacetime and Robertson-Walker spacetime, and he explains the opportunity that led him to the University of London, where black holes was a focus of research. He describes meeting Paul Davies and Chris Isham and how the field started to take black holes seriously as observable entities in the 1980s. Fulling explains his longstanding interest in asymptotic expansion and he surveys more recent advances in the Casimir effect. He reflects on the Unruh effect as it approaches its 50th anniversary, and he addresses the disagreement on whether or not it has been observed and whether the Unruh effect implies Unruh radiation. At the end of the interview, Fulling discusses his current interests in the soft wall problem and acceleration radiation, and he explains his ongoing interest in seeing advances in research on Casimir energy.