Plan execution monitoring in dynamic and uncertain domains is an important and difficult problem. Multi-agent environments exacerbate this problem, given that interacting and coordinated activities of multiple agents are to be monitored. Previous approaches to this problem do not detect certain classes of failures, are inflexible, and are hard to scalp up. We present a novel approach, SOCFAD, to failure detection and recovery in multi-agent settings. SOCFAD is inspired by Social Comparison Theory from social psychology and includes the following key novel concepts: (a) utilizing other agents in the environment as information sources for failure detection, (b) a detection and repair method for previously undetectable failures using abductive inference based on other agents' beliefs, and (c) a decision-theoretic approach to selecting the information acquisition medium. An analysis of SOCFAD is presented, showing that the new method is complementary to previous approaches in terms of classes of failures detected.