This essay offers an explanation of how assertions express that the speaker has a propositional attitude toward what's asserted. The explanation is that this feature of assertion is owed to a hearer's spontaneous mindreading. I call this the assertoric mindreading hypothesis . Once developed and defended, the hypothesis is used to investigate which attitude is expressed. Since the attitude expressed is the attitude tracked during mindreading, the attitude must have a certain profile. It is argued that only factive attitudes like knowledge have this profile. Non‐factive attitudes like belief or acceptance are ineligible.