Accurately assessing other people’s perspective in general, and other people’s emotional responses in particular, is essential for successful social interaction. However, substantial research finds that accurate perspective taking is the exception rather than the norm. Although errors in perspective taking are common, little is known about their consequences. Is it worse to overestimate or to underestimate other people’s emotional responses? Seven experiments find that underestimating the intensity of other people's emotional responses leads to more negative evaluations than overestimating others’ emotions (Experiments 1–5). These results replicate across emotional valence and across observers and targets and occur because people believe that underestimation is indicative of lower effort and empathy in trying to understand the target. Additional experiments identify moderators of these effects, including stereotypical emotions and socially undesirable emotions (Experiments 6–7). The cost of errors in affective perspective taking is asymmetric, leading to important implications for social coordination.