2021

Program Chair: Conference on Complex Systems (CCS), The Web Conference (TheWebConf)
Advisory Board: Amazon-USC Center for Trusted Computing

2019

Program Chair: Web Search and Data Mining (WSDM2019), PhD Symposium at TheWebConf
Advisory Board: Twitter Academic Relations

2016

General Chair, Social Informatics Conference (SocInfo'2016).
Tutorial Chair,  International AAAI Conference on Weblogs and Social Media (ICWSM'2016).
Organizer, IPAM Culture Analytics workshop (UCLA).

2014

Program Chair, Social Informatics (Barcelona)
Program Chair, 7th ASE/IEEE Social Computing Conference (Beijing)
Organizer, IPAM workshop on Mathematics of Social Learning (UCLA)

2010

Senior Program Committee Member, International AAAI Conference on Weblogs and Social Media, 2010.

2009

Program Committee Member, International AAAI Conference on Weblogs and Social Media, 2008-2009.

Program Committee Member, International Joint Conferences on Artificial Intelligence, 2009.

Program Committee Member, International World Wide Web Conference, 2008-2009.

Program Committee Member, International Conference on Machine Learning, 2009.

Program Committee Member, IEEE International Conference on Social Computing, 2009.

Reviewer, Information & Intelligent Systems Panel, NSF, 2008-2009.

Reviewer, Journal of the American Society for Information Science and Technology, 2009.

Reviewer, VLDB Journal, 2009.

2008

Program Committee Member, AAAI, 2008.

Reviewer, ANTS, 2008.

Reviewer, Journal of Artificial Intelligence Research, 2008.

Reviewer, International Journal of Cooperative Information Systems, 2008.

Reviewer, Swarm Intelligence Journal, 2008.

Reviewer, Journal of Agents and Multi-Agent Systems, 2008.

Reviewer, International Journal of Modelling, Identification And Control, 2008.

Reviewer, ACM Transactions on Knowledge Discovery and Datamining, 2008.

Reviewer, Journal of American Society for Information Science and Technology, 2008.

Reviewer, Transactions on Robotics, 2008.

Organizer, 2008 AAAI Spring Symposium on Social Information Processing, March 26-28, 2008.

2006-2000

Program Committee Member, Annual Autonomous Agents and Multi-Agent Systems, AAMAS, 2004-2006.

Publications Chair, 2005 IEEE Swarm Intelligence Symposium, Pasadena, CA, June 6-8, 2005.

Co-Organizer, Communications Networks (CN02) program and workshops, Institute for Pure and Applied Mathematics (UCLA), March 11, 2002 - June 9, 2002.

Member, Search committee for Editor-In-Chief,

Committee Member, Large Scale Dynamic Heterogeneous Databases workshop, IJCAI, 2001.

Panelist, NSF ITR review, May 2000.