The 3rd Annual International Conference on Computational Social Science (IC2S2 2017) is an interdisciplinary event designed to engage a broad community of researchers – academics, industry experts, open data activists, government agency workers, and think tank analysts – dedicated to advancing social science knowledge through computational methods. IC2S2 2017 affords the opportunity to meet and discuss works in which social systems and dynamics are investigated in a quantitative way through large datasets that are either mined from various sources (e.g. social media, communication systems), or created via controlled experiments or computational modeling. After successful events in Helsinki 2015 and Evanston, IL 2016, the 3rd IC2S2 will take place in Cologne, Germany.