Monitoring is the study of a system at runtime, looking for input and output events to discover, check or enforce behavioral properties. Interactive debugging is the study of a system at runtime in order to discover and understand its bugs and x them, inspecting interactively its internal state.Interactive Runtime Veri cation (i-RV) combines monitoring and interactive debugging. We de ne an e cient and convenient way to check behavioral properties automatically on a program using a debugger. We aim at helping bug discovery while keeping the classical debugging techniques and interactivity, which allow understanding and xing bugs.CCS Concepts: •Software and its engineering → Software testing and debugging;