Previously, he was a visiting scholar at Google, and a postdoctoral scholar in the computer science department at Stanford University advised by Christopher Ré. He received his Ph.D. in computer science from the University of Maryland, where he was advised by Lise Getoor. His research focuses on statistical machine learning methods that exploit high-level knowledge like rules and programs. Stephen's thesis on probabilistic soft logic was recognized with the University of Maryland's Larry S. Davis Doctoral Dissertation Award.