AAAI Spring Symposium on Observational Studies in Social Media and other human-generated content (OSSM). Co-organizer.
Intl Conf. on Weblogs and Social Media (Steering committee chair; Senior PC 2016, 2015, 2014; General Chair 2013; PC 2012, 2011)
KDD 2015, PC.
WWW 2015 (Crowdsourcing and Social Media track) 2014, 2013, Social Networks and Graph Analysis track, TPC.
WSDM 2015, 2012, PC; Workshop on Language in Social Media (LSM 2011, 2012) PC; Symp. on Cloud Computing (SOCC 2011) PC; Intl. Conf. on Dependable Systems and Networks (DSN 2010,2011) PC; Usenix Webapps (WebApps 2011, 2012) PC; Intl. Conf. on Autonomic Computing (ICAC 2008-2012) PC, PC Chair in 2010.