BiCollege cooperation allows Bryn Mawr students to major at Haverford, and Haverford students to major at Bryn Mawr. At Haverford, major declaration is limited to the spring semester, so Bryn Mawr students will not be allowed to officially declare a Haverford major until the spring. Haverford also does not use the same online process as Bryn Mawr does. Please reference information and instructions here.
If you are debating between the Bryn Mawr and Haverford departments in a particular field, be sure to talk with faculty members and declared majors in each department.