Earth System Science is a relatively young department at UCI. It originated in 1986 as an initiative by School of Physical Sciences faculty, who proposed formation of an interdisciplinary graduate level program in geosciences, with an emphasis on global environmental change. The founding chair, Ralph Cicerone, joined the faculty in 1989 and by 1993 recruited 5 additional faculty with interests in global environmental change and specializing in atmospheric chemistry and biogeochemistry. The initial ESS faculty developed goals and an initial curriculum, and began offering courses during the 1993-94 academic year. Graduate students who joined the Earth System Science program prior to 1995 were rostered largely in the Department of Chemistry. Laboratories have been built, and a wide range of research is underway. The name of the program was changed to Earth System Science to better describe our emphasis. A proposal to offer Ph.D. degrees was submitted in March 1994, was approved by the System-wide Faculty Senate in February 1995, and received final approval by the Office of the President in June 1995. The UCI Faculty Senate approved a proposal requesting a change from Program to Department Status in June 1995.