Adas is the UK’s largest independent agricultural and environmental consultancy and provider of rural development and policy advice. ADAS provides independent science-based research, consultancy and contracting services to a wide range of organisations in both the private and public sectors, throughout the UK and internationally.

The UK's National Agricultural Advisory Service (NAAS) was established in 1946 as the advisory and research arm of the Ministry of Agriculture, Fisheries and Food (MAFF) because of the harsh food rationing of World War II that continued in the UK into the early 1950s. Plant pathology, entomology, soil and other specialist advisers throughout the country advised farmers and growers how to maximise their output.

The NAAS was rebranded as ADAS in 1971. In 2016 the business, operating assets and employees of ADAS were acquired by environmental consultancy, RSK