It was founded in 1948 as a voluntary charitable organisation dedicated to conserving the wildlife and wild places of Lincolnshire and to promoting the understanding and enjoyment of the natural world.
It has over 27,000 members and manages 95 nature reserves with a total area of 8,520 acres (34.49 km2).
The area groups also organise meetings, visits and social events and are involved in fundraising and membership recruitment.
5,000 of the Trust's members are under 16 years of age; these are catered for by the organisation's junior wing Wildlife Watch which runs seven groups around the county organising events for children.
The Trust's income is derived mainly from members' subscriptions, money raised by area groups and members, donations, grants from local authorities and government agencies (usually for special projects), profits from the Trust's sales business and from legacies.