The Mississippi Ornithological Society was established in 1955 to encourage ornithological research, to promote greater appreciation and conservation of native birds, and to collaborate with like-minded organizations.

Today, MOS functions as a birder group. It provides a welcoming space for all who are interested in wild birds in Mississippi, both hobbyists and professional scientists. There is often overlap with broader nature study as well. MOS holds spring and fall meetings, publishes a newsletter and a journal (The Mississippi Kite), archives rare bird records, and maintains a checklist of the birds of Mississippi.