Antibodies and antigen-binding fragments thereof that bind to human PAC1 are provided. Nucleic acids encoding the antibodies and antigen-binding fragments thereof, vectors, and cells encoding the same are also provided. The antibodies and antigen-binding fragments thereof can inhibit binding of PAC1 to PACAP, and are useful in a number of PAC1 related disorders, including the treatment and/or prevention of headache disorders, including migraine and cluster headache.