QEII was established under the Queen Elizabeth the Second National Trust Act 1977 to aid conservation on private land. The purpose of the Act is "to encourage and promote, for the benefit of New Zealand, the provision, protection, preservation and enhancement of open space."

Open space is defined in the Act as 'any area of land or body of water that serves to preserve or to facilitate the preservation of any landscape of aesthetic, cultural, recreational, scenic, scientific, or social interest or value.'

The Act enables QEII to:

• Negotiate and administer open space covenants (or protection agreements) with landowners,
• Acquire and manage land,
• Provide financial grants for open space projects, and
• Advocate open space protection through advice, research and information.

The Trust is a statutory organisation independent from Government and managed by a Board of Directors.