How emotions are connected, shared and exchanged between people over time signals important relationship processes and also impacts people’s individual wellbeing. To promote a better understanding of the involved processes and mechanisms, we propose a framework that captures four key characteristics of interpersonal emotion dynamics. We distinguish between characteristics that capture only the interpersonal emotional aspects versus characteristics that capture the interpersonal system as a whole (taking into account both intrapersonal and interpersonal emotional aspects), and between characteristics that capture the time-dependent versus time-independent aspects of emotion dynamics. Combined, this results in the following four characteristics of interpersonal emotion dynamics: (1) emotional covariation, or how emotions of different individuals covary across time, (2) emotional influencing, or how a change in one individual’s emotions predicts other people’s subsequent emotional change, (3) emotional variability, indicating the extent of fluctuations in the interpersonal emotion system, and (4) emotional inertia, representing the carryover of the emotional state of the interpersonal system over time. For each, we synthesize existing research on these characteristics, their relation with (mal)adjustment indicators, underlying processes, and current gaps in research.