This book constitutes the refereed proceedings of the International RuleML Symposium, RuleML 2012, held in Montpellier, France, in August 2012 - collocated with the 20th biennial European Conference on Artificial Intelligence, ECAI 2012. The 14 full papers, 8 short papers and 2 track papers presented together with 2 keynote talks were carefully reviewed and selected from numerous submissions. The accepted papers address topics such as business rules and processes; rule-based event processing and reaction rules; rule-based policies and agents on the pragmatic web; rules and the semantic web;...