The history of academic dress reaches far back into the early days of the oldest universities. A statute of 1321 required that all “Doctors, Licentiates, and Bachelors” of the University of Coimbra wear gowns. It is still a vexing question whether academic dress finds its sources chiefly in ecclesiastical or in secular dress. Gowns may have been necessary for warmth in the unheated buildings frequented by medieval scholars. Hoods seem to have served to cover the tonsured head until they were superseded for that purpose by the skull cap. This was itself displaced by a headdress more or less like one or another of those now recognized as “academic.” 

Over the many years of development, a great diversity of academic apparel made its appearance. When American colleges and universities desired to adopt some suitable system of academic apparel more than a century ago, it seemed to them best to agree on some definite system which all might follow. Accordingly, there was held on May 16, 1895 at Columbia University a conference of representatives of the governing boards of various interested institutions. The outgrowth of that meeting was the establishment of “The Academic Costume Code.” The code has been revised several times since its initial approval. The most recent update was in 1986. In nearly every instance of the many hundreds of colleges and universities of the United States which have adopted academic dress, the standards thus prescribed have been adopted and followed, either wholly or at least in the main.

The academic costume code recognizes three styles of gowns: a bachelor’s gown, a master’s gown, and a doctor’s gown. In conjunction with its centennial celebration in May 2000, the Graduate College inaugurated a new doctor’s gown. The differences in these gowns are mainly in the cut and shape of the sleeves and in the trimming.Hoods are also recognized for each of the above degrees. They vary in shape, size, and length, the larger and more elaborate designating the doctoral level. The shell of the hood matches the black material of the gown, and is lined with the color or colors of the institution conferring the degree—in the instance of The University of Iowa, old gold. The velvet border of the hood is of a color indicative of the field of learning to which the degree pertains.

An abbreviated list of these colors as they apply to The University of Iowa follows: 
Arts and Letters, white 
Business and Accounting, sapphire blue
Dentistry, lilac
​Engineering, orange
​Law, purple
​Medicine, green
​Music, pink
​Nursing, apricot
​Pharmacy, olive green
​Philosophy, dark blue
Public Health, salmon
​Science, golden yellow

The Oxford cap, proper for all degrees, is worn both indoors and outdoors with academic costume. The tassel, worn over the left eye, is also symbolic of the degree to be conferred on the wearer and conforms to the code colors for hood trimming.

Practice at The University of Iowa varies slightly from that established by the code. Candidates for degrees may be identified with the colleges from which they are to secure their degrees by the color of the tassels they wear. Colleges are designated by tassel colors as follows: 
Business, sapphire blue
​Dentistry, lilac
​Engineering, orange
​Graduate, black 
Law, purple
​Liberal Arts and Sciences and University College, white 
Medicine, green
​Nursing, apricot
​Pharmacy, olive green

Only candidates for the doctoral-level degrees (Doctor of Philosophy, Doctor of Audiology, Doctor of Musical Arts, Doctor of Physical Therapy, Doctor of Dental Surgery, Doctor of Medicine, Juris Doctor, and Doctor of Pharmacy) wear hoods. The velvet trim on the hoods for these degrees conforms to the colors set forth in the intercollegiate code, and, with the exception of the Doctor of Philosophy, the Doctor of Musical Arts, the Doctor of Audiology and the Doctor of Physical Therapy hoods, are the same color as the tassel. The Doctor 
of Audiology and the Doctor of Physical Therapy are trimmed in teal. The Doctor of Philosophy hood is trimmed in blue, the color appropriate to philosophy, and the Doctor of Musical Arts hood is trimmed in pink, the color for music. In all four cases,the tassel worn is black.