This book constitutes the refereed proceedings of the Third International Conference on Social Computing, Behavioral Modeling, and Prediction, SBP 2010, held in Bethseda, MD, USA, in March 2010. The 26 revised full papers and 23 revised poster papers presented together with 4 invited and keynote papers were carefully reviewed and selected from 78 initial submissions. The papers cover a wide range of interesting topics such as social network analysis, modeling, machine learning and data mining, social behaviors, public health, cultural aspects, effects and search.