In the often unheated buildings of the middle ages, long gowns were necessary for scholars to ward off the cold.
Academic dress for graduations started in the 12th and 13th centuries when universities first began forming. Whether a student or a teacher, standard dress for scholars was clerical garb. Most medieval scholars had made certain vows, and had at least taken minor orders with the church so clerical robes were their main form of dress to begin with.
In 1321, the University of Coimbra mandated that all Doctors, Bachelors, and Licentiates must wear gowns. In the latter half of the 14th century, excess in apparel was forbidden in some colleges and prescribed wearing a long gown. By the time of England's Henry VIII, Oxford and Cambridge began using a standard form of academic dress, which was controlled to the tiniest detail by the university.
Not until the late 1800s were colors assigned to signify certain areas of study, but they were only standardized in the United States. European institutions have always had diversity in their academic dress, but American institutions employ a definite system of dress thanks to Gardner Cotrell Leonard from Albany, New York. After designing gowns for his 1887 class at Williams College, he took an interest in the subject and published an article on academic dress in 1893. Soon after he was asked to work with an Intercollegiate Commission to form a system of academic apparel.
The system Gardner Cotrell Leonard helped form was based on gown cut, style and fabric; as well as designated colors to represent fields of study. For example green was the color of medieval herbs, and was assigned to medical studies. Because olive is close to green, was designated for pharmaceutical studies.
In 1959, the American Council on Education had a Committee on Academic Costumes and Ceremonies review the costume code and make changes. In 1986, the committee changed the code to clarify the use of dark blue for a Doctor of Philosophy (Ph.D.)
The shape and size of the hood and the sleeve design of the gown show the degree a student pursued: a Bachelor's Degree gown has pointed sleeves and no hood, a Master's Degree gown had long, closed sleeves with arm slits and a narrow hood, and a Doctor's Degree had bell-shaped sleeves and a draped, wide hood.
The color of the hood's lining tells which college or university the degree was given by. For example: Harvard is crimson, Temple is cherry and white, and Cornell is purple and white. However, other than the lining, the hood must be black.
Caps should only be made of black cotton poplin, broadcloth, rayon, or silk, to match gown they are to be used with. Velvet may only be used for a doctor's degree.
Tassels should be fastened to the middle of the cap's top and allowed to lie where it will. It should be black, or the color of field of study, unless it is for a doctor's degree in which case is may be gold.