Three sets of studies provide evidence for an illusion of transparency, or a tendency for people to overestimate the extent to which others can discern their internal states. People often mistakenly believe that their internal states "leak out" more than they really do. The authors attribute this bias to a tendency for people to adjust insufficiently from the "anchor" of their own phenomenological experience when attempting to take another's perspective. Evidence for this illusion is provided by showing that liars overestimate the detectability of their lies (Studies 1a, 1b, and 1c) and that people believe their feelings of disgust are more apparent than they actually are (Studies 2a and 2b). A final pair of experiments (Studies 3a and 3b) explores the implications of the illusion of transparency for people's reluctance to intervene in emergencies. All 3 sets of studies also provide evidence consistent with the proposed anchoring and adjustment interpretation.