After a post-doctoral position at UC Berkeley, Kayser was an assistant professor at the State University of New York at Stony Brook from 1966 to 1969, when he joined the physics department at Northwestern University as associate professor. In 1972, Kayser joined the
National Science Foundation, where he was the program director for theoretical physics. While there, he helped establish the
Kavli Institute for Theoretical Physics at
University of California, Santa Barbara. He left the editor position in 2009. While working at NSF, he became interested in researching
neutrinos and was principal author of a book, "The Physics of Massive Neutrinos". He retired from the NSF in 2001, after which he joined
Fermilab as a distinguished guest scientist. While at Fermilab, he served on a variety of committees, including the Particle Physics Project Prioritization Panel (2002–2007) and the Fermilab Physics Advisory Committee (2004–2008). In 2009, he was elected the
chair of the
American Physical Society's Division of Particles and Fields. He officially retired from Fermilab at the end of 2012. ==Personal life==