After earning his Ph.D. at Chicago he conducted post-doctoral work at the University of Cambridge. From 1971 to 1995, Ostriker was a professor at Princeton, and served as Provost there from 1995 to 2001. From 2001 to 2003, he was appointed as Plumian Professor of Astronomy and Experimental Philosophy at the Institute of Astronomy, Cambridge. He then returned to Princeton as the Charles Young Professor of Astronomy and is now the Charles A. Young Professor "Emeritus". He continues as a Senior Research Scholar at Princeton and became a Professor of Astronomy at Columbia in 2012.