Thomas Eddy Tallmadge was born in Washington, D.C. on April 24, 1876. His family moved to the Chicago suburb of Evanston, Illinois in 1880 where he was raised and graduated from Evanston High School in 1894. He then attended the Massachusetts Institute of Technology where he earned a Bachelor of Science degree in Architecture in 1898. He returned to Chicago and obtained employment as a draftsman in the office of Daniel H. Burnham and Company. Tallmadge was with Burnham for seven years when he won the Falkenau Traveling Scholarship presented by the Chicago Architectural Club in 1904 for his entry "A Crèche in a Manufacturing District". He then spent the summer sketching architectural scenes across Europe.

After his return from Europe he decided to leave the office of D.H. Burnham and Company, and along with fellow draftsman Vernon S. Watson, they formed a partnership in October of 1905. They opened their office in the Ashland Block building at the northeast corner of Clark and Randolph Streets in Chicago, Illinois and later moved their practice to the Security Building at 189 West Madison Street, where they continued their partnership for 31 years. The firm soon developed a reputation for designing modest suburban prairie style residences primarily in Evanston and Oak Park, Illinois. Their first commission of importance came in 1909 with the design of the First Methodist Church in Evanston, Illinois. This was the first of over thirty churches that would be designed by the partnership which by 1914 was known more for their ecclesiastical rather than their residential architecture.

Vernon Watson was the chief designer but Tallmadge was more widely known because of his activities as an architectural historian and teacher. In 1906 Tallmadge became an instructor of architectural design and history at the Armour Institute (now known as the Illinois Institute of Technology), a position he held for twenty years. In 1908 he coined the term "The Chicago School" in an article of the same name written for a magazine called Architectural Review. The termed was used to describe Frank Lloyd Wright and his contemporaries who designed primarily prairie style residences after the turn of the century. Tallmadge also had written three books on the subject of architectural history, "The Story of Architecture in America", "The Story of England’s Architecture" and "Architecture in Old Chicago".

After Vernon Watson retired in 1936, Tallmadge practiced alone in his studio at 19 East Pearson Street in Chicago with the exception of a men’s dormitory commission at Ripon College which he designed with a 1930 Armour Institute graduate named William Alderman. Tallmadge was also known for designing a street light in the 1920's that is still in use today in Evanston and Oak Park. On January 1, 1940 Thomas Eddy Tallmadge was killed in a train accident near Arcola, Illinois. He was buried in Graceland Cemetery in Chicago, Illinois.