This book constitutes the proceedings of the International Joint Conference on Rules and Reasoning, RuleML+RR 2018, held in Luxembourg during September 2018. This is the second conference of a new series, joining the efforts of two existing conference series, namely “RuleML” (International Web Rule Symposium) and “RR” (Web Reasoning and Rule Systems). The 10 full research papers presented together with 5 long technical communications and 7 short papers were carefully reviewed and selected from 33 submissions.