The Connecticut (CT) Valley Branch of the American Society for Microbiology (ASM) was founded in 1922, making it and the Washington D.C. Branch the oldest branches of the ASM. The first president of the CT Valley Branch was Dr. Leo F. Rettger of Yale University.  The CT Valley Branch is also known as the Leo F. Rettger Society in Dr. Rettger's honor. 

The CT Valley Branch of the ASM promotes scientific knowledge of microbiology through discussion of scientific research and education in microbiology and related subjects.

The Connecticut Valley includes all zip codes in the states of Connecticut and Rhode Island, and parts of New Hampshire (zip code areas 03400-03499 and 03600-03799) and Massachusetts (zip code areas 01000-01699). If you are a microbiologist living, working, or studying in Connecticut or Rhode Island, in central or western Massachusetts, or in New Hampshire's Cheshire or Sullivan counties or along the Connecticut River as far north as Woodsville, we cordially invite you to join our Branch.