Indiana pathologists formally organized on September 26, 1933 at the French Lick Hotel in French Lick, Indiana, as the Indiana Laboratory Association. Among their objectives were facilitating discussion with each other regarding advancements and improvements in the field of pathology, the standardization of laboratory methods, and to promote the practice of scientific medicine by a wider application of clinical and public health laboratory methods." The organization originally included members with three years of post-graduate experience in laboratory sciences. Additionally, an associate level consisting of registered technicians approved by the American Society of Clinical Pathologists Board of Registry plus Honorary designees who made note-worthy contributions to the laboratory sciences made up the early membership.

In 1935, the name Indiana Association of Pathologists was adopted and the Associate level of laboratory technicians was removed. 

The annual slide conference began in 1949. The conference now bears the name the IAP Spring Slide Seminar. The IAP became officially incorporated with the State of Indiana in 1957.

a)  To maintain high standards of the practice of medicine through the provision of state-of-the-art pathology expertise and laboratory medicine excellence.

b)  To stimulate through education, scientific investigation, and promulgation the results of research both basic and applied in the area of laboratory medicine.

c)  To promote the practice of scientific medicine by a wider application of clinical and public health laboratory methods to the diagnosis, treatment and prevention of disease.

d)  To promote public knowledge and understanding of the practice of pathology as it relates to the individual, the community, and to the totality of medicine.

e)  To have and exercise all of the powers conferred by law upon not-for-profit organizations including the right to receive gifts, bequests, and contributions of all kinds in nature for the accomplishment of the above purposes.

f)  To own such property as may be necessary or convenient to account for the above purposes.