As humans, we spend much of our time going beyond the here and now. We dwell on the past, long for the future, and ponder how things could have turned out differently. In this talk, I will argue that people's knowledge of the world is organized around causally structured mental models, and that much of human thought can be understood as cognitive operations over these mental models. Specifically, I will highlight the pervasiveness of counterfactual thinking in human cognition. Counterfactuals are critical for how people make causal judgments, how they explain what happened, and how they hold others responsible for their actions.