Connecticut Training School for Nurses was the third training school established in the United States, after the model of Florence Nightingale's training school for nurses in England.

On April 17, 1873 the committee of directors of New Haven Hospital made a report stating that "if a Society is organized for the training of nurses, the Directors of the General Hospital Society of Connecticut are hereby authorized and advised, under suitable regulations, to afford to said Society such facilities for the instruction of Nurses as can be given at the Hospital, consistent with the proper management of and general interests of the Hospital".

The first class was admitted in the fall of 1873, with four pupils and a head nurse. Connecticut Training School for Nurses was the first independent school to be chartered; its relations with New Haven Hospital were regulated by an agreement. The school agreed to do all the nursing for the hospital, and the hospital in turn agreed to supply board, lodging, and laundry for the nurses.

Until 1918 the entrance requirement was one year of high school. Service, meeting the needs of the hospital and physicians prevailed over education. The course of training had a duration of twelve months. After a month's vacation, the nurses were expected to go into five months private nursing in families and turn their earnings over to the school.

Mr. Charles H. Thomson, Mrs. Georgiana Woosley Bacon, Dr. Francis Bacon, Dr. George B. Farnam, Mrs. Noah Porter, who was the president of the school for seventeen years, Mrs. T. W. T. Curtis, Mrs. C. B. Richards, Miss Emily Betts were some of the people who made efforts to carry the school through its formative years.

Connecticut Training School for Nurses, with 87 students in 1914 and 85 in 1915, participated in World War I by sending eleven of its graduates overseas in Dr. Flint 's Mobile Unit, in 1917.