Over recent years, under the initial umbrella of the Royal Society of New Zealand, a diverse group of individuals and organisations have met in order to progress sustainable development in New Zealand.

This group met under the name 'Sustainable Development Forum'. At the same time, a separate group under the name of 'Sustainable New Zealand' was meeting in Rotorua and Auckland with very similar objectives.

In 2005, the two groups merged under the name Sustainable Aotearoa New Zealand (SANZ), which was incorporated as a charitable trust.

In 2006, UNESCO (United Nations Educational, Scientific, and Cultural Organization) asked SANZ to convene a national forum with the purpose of establishing a ten year vision for sustainable development and education in New Zealand. The first forum lead to a wider one, involving representatives from many sectors of society. 

Finally, in 2008 three think tank workshops were held to come up with tangible deliverables for sustainability in New Zealand, out of which the paper Strong Sustainability for New Zealand: Principles and Scenarios was born. 

The paper was reviewed by 13 New Zealand and international experts working in the field of sustainability, including Jonathon Porritt, Founder Director Chairman of the UK Sustainable Development CommIssion.

In May 2010 SANZ adopted phase2 as its public name to better reflect the organisation's core vision of promoting and facilitating society's transition to strong sustainability.

Phase2 is run by an elected board committed to facilitating the realisation of strong sustainability throughout society.