The work of the organisation includes policy recommendation and campaigning in the built and natural heritage areas, the holding in trust of relevant properties, and environmentally-relevant education.

[5] The meeting resolved to create such a body, and elected both a provisional committee, and a council of 16 plus 4 co-opted members, who secured bankers, auditors and solicitors.

[6]: 21 An Taisce was concerned with questions about properties such as Muckross House, Kanturk Castle and Derrynane House, plans for North Bull Island and other nature reserves, and Saint Anne's Park, tree preservation and the work of the Electricity Supply Board and Bord na Mona; in 1951, the UK National Trust agreed to lease Kanturk Castle to An Taisce.

The organisation supported the extension of the powers of Bord Failte to protect historic properties and places of scenic or other special interest in 1952, which was also the year it considered the question of what would much later become its headquarters, the Tailors' Hall.

In 1962 it received a ministerial request to agree to be formally consulted on questions of nature and amenity conservation, and in 1964 it was given an advisory role supporting local authorities which had defunct quarries in their areas.

[6]: 29–32 By 1965, the organisation was becoming involved in more planning and development referrals, both impacting natural sites, from the Bourne Vincent Memorial Park and the Cliffs of Moher to Booterstown marsh and Bull Island, and the built environment, such as around Mountjoy Square in Dublin.

The routine administration of the organisation moved from volunteers' homes to offices on Baggot Street, and it formally requested legal powers like those of the National Trust in Britain.

Towards the end of the decade, An Taisce received 5,500 acres of land in County Donegal, and a lease and management rights over much of the undeveloped part of Howth Head, and Ireland's Eye.

[6]: 38–39 In 1972, the body sought provision for environmental impact assessments for large developments, and in 1973 it appointed its first full-time director and opened an office in Cork.

In 1974, a Heritage Gardens Committee was formed and membership approached 7,400, with 27 active local associations, while An Taisce co-founded the European Environmental Bureau.

In 1975, the organisation began planning what would become the Irish Architectural Archive and membership passed 8,000; suggestions it made were incorporated into several pieces of legislation.

Also in 1982, An Taisce was formally recognised as a charity by the Irish Revenue Commissioners, and the six local associations operating within the city and county of Dublin formed an umbrella body.

A policy document on forestry was produced, and a conference on the topic hosted (resulting in a further publication the following year), while the organisation continued active engagement on the future of Irish bogs.

In 1994, the major County Donegal property was placed on a long lease with the Irish government, to be operated as part of Glenveagh National Park until at least 2093.

An ecumenical service of thanksgiving at St Patricks's Cathedral, as well as the planting of 50 oak trees in the Phoenix Park, also formed part of the commemoration.

Celebrations continued through 1997, including a joint event with the National Trust, and a closing function with the Taoiseach, Bertie Ahern attending as the guest of honour.

[6]: 64–65 The Office of Public Works agreed in 1998 to maintain Tailors' Hall in return for up to 100 days of use each year of its function rooms, to be administered by the Dublin Castle conference centre unit.

Conflict emerged within An Taisce's governing council, as many members wanted to pursue what they saw as a more active agenda promoted by a new NGO, Friends of the Irish Environment.

In 1999, Kanturk Castle was fully made over to An Taisce by the National Trust, while major planning applications addressed included what would later become the Trump golf resort at Doonbeg.

It seeks to educate, inform, and lead public opinion on the environment, to advocate and influence policy, and to manage a portfolio of heritage properties.

Overall steering of the organisation is in the hands of a council,[20] which in turn elects a board of directors (charity trustees),[21] and other internal policy and operational committees.