The Chennai Metropolitan Development Authority (CMDA), formerly known as the Madras Metropolitan Development Authority (MMDA), is the nodal planning agency of Chennai in the Indian state of Tamil Nadu. The CMDA administers the Chennai Metropolitan Region, spread over an area of 1,189 km2 (459 sq mi) and covers the districts of Chennai, Thiruvallur and Kancheepuram. It was set up for the purposes of planning, co-ordination, supervising, promoting and securing the planned development of the Chennai Metropolitan Area. It coordinates the development activities of the municipal corporations, municipalities and other local authorities.
The CMDA was constituted as an ad hoc body in 1972 under the Tamil Nadu Town and Country Planning Act 1971. It was formed as the nodal Town planning authority for the city of Madras (now Chennai) and its suburbs and became a statutory body in 1974. It is headed by minister for housing as its chairman.
In January 2013, CMDA was recognised as a research centre by the Centre for Research, Anna University.
The CMA falls in three Districts of the Tamil Nadu State viz. Chennai District, part of Thiruvallur District, and part of Kancheepuram District. The extent of the Chennai District (covered in Chennai Municipal Corporation area) is 176 sq.km and comprises 55 revenue villages in five Taluks viz. (i) Fort-Tondiarpet Taluk, (ii) Perambur-Purasawalkam Taluk, (iii) Egmore-Nungambakkam Taluk, (iv) Mambalam-Guindy Taluk and (v) Mylapore-Triplicane Taluk. In Thiruvallur District out of total district area of 3427 sq.km, 637 sq.km. in Ambattur, Thiruvallur, Ponneri and Poonamallee taluks fall in CMA. In Kancheepuram Districtout of 4433 sq.km, 376 sq.km in Tambaram, Sriperumbudur and Chengalpattu Taluks fall in the Metropolitan area. New construction in areas under the CMDA needs their approval to start work