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.