Ann was born Dec. 1, 1813 in the Quaker settlement of West Grove in Pennsylvania near Philadelphia. She attended school but also helped care for her six younger siblings as her mother's health was poor. She was also active in the local anti-slavery society.
When her siblings grew to be more independent she began teaching. At this time she also became interested in physiology and recognizing the need for more information on the subject, she initiated classes in female physiology and hygiene for women and girls.
In 1847 she embarked on a two year apprenticeship with Dr. Nathaniel Moseley in Philadelphia. Completing the apprenticeship she applied to four medical colleges in Pennsylvania but was rejected solely because she was female. In 1850 a group of Quakers founded the Woman's Medical College of Pennsylvania to meet the needs of the many women seeking a career in medicine. Just shy of her 37th birthday, Ann enrolled in the first class with seven other women.
After graduating she remained at the college as a professor of physiology and hygiene. In 1858 she initiated a fundraising campaign to build a woman's hospital in connection with the college to provide hands on clinical instruction.
In 1866 Ann was appointed dean of the Woman's Medical College, the first woman to hold that position. She applied for permission for her students to attend general clinics at the Philadelphia Hospital but was met with demonstrations by male medical students protesting the impropriety of educating men and women in medicine together. She fought this narrow-mindedness saying women were patients and it was "in accordance with the instincts of the truest womanhood for women to appear as physicians and students." Philadelphia newspapers published her comments.