Before joining Penn, he was a research faculty member at the Center for Language and Speech Processing at Johns Hopkins University for 6 years. He served as the General Chair of the ACL 2017 conference, and the Program Co-Chair for the EMNLP 2015 conference. He has served as the Chair of the NAACL Executive Board, the Secretary-Treasurer for SIGDAT, and on the editorial boards of TACL and Computational Linguistics. He has more than 100 publications, which have been cited over 14,000 times. He is a Sloan Research Fellow, and he has received faculty research awards from Google, Microsoft, Amazon and Facebook in addition to funding from DARPA and the NSF. His research interests include natural language processing and crowdsourcing.