Professor O'Brien earned his B.S. in Psychology (1967) from Pomona College and his M.S. (1970) and Ph.D. (1973) in Sociology from the University of Wisconsin. He taught at California State College at San Bernardino from 1973 to 1981 and joined the faculty at the University of Oregon in 1981. He has served as Department Head at both San Bernardino and Oregon and as Associate Dean in the College of Arts & Sciences (with oversight for the social sciences and curriculum) for three years (1998-2001). Professor O'Brien's current project (with Jean Stockard) provides an explanation for shifts in age distribution of both homicides (offenses and deaths) and suicides.