The Active Ageing Index (AAI) was a project managed jointly by the European Commission's Directorate General for Employment, Social Affairs and Inclusion (DG EMPL), and the Population Unit of the United Nations Economic Commission for Europe (UNECE).

The first phase of the project was implemented from January 2012 to February 2013. Its major outcome was a release of AAI results for 27 European Union countries. The main developer of the 2012 AAI was the European Centre for Social Welfare Policy and Research in Vienna. The 2012 AAI was presented to policymakers, civil society, researchers and other stakeholders at numerous international meetings, conferences and fora and recognized as a successful tool which needs to be further extended and applied.

AAI-II started in October 2013 and continued through April 2016. Under the second phase, the AAI coverage was extended to Croatia and four non-EU countries, namely Canada, Iceland, Norway, and Switzerland. The coverage was also extended in time with the 2010 and 2014 AAI calculated based on 2008 and 2012 data respectively. Two pilot studies at national level were carried out for Serbia and Turkey, and a pilot study at local level was implemented in Germany. Numerous initiatives to compute and apply AAI at both national and subnational levels emerged throughout the second phase. A number of events were organised, including an international seminar in April 2015, national seminar in Lithuania in May 2015, two peer reviews on subnational application of AAI, and others. The AAI indicators were included into the statistical annex to national reports on implementation of the Madrid International Plan of Action on Ageing (MIPAA). An analytical report on the AAI results and trends up to 2014 AAI was issued in 2015.

The third phase of the project was launched in May 2016 and concluded in August 2019. Under this phase 2016 and 2018 AAI were calculated (based on 2014 and 2016 data respectively); 2018 AAI was calculated also for North Macedonia, Norway, and Serbia. AAI was calculated at subnational level for Romania and Spain. Three studies on AAI calculated for different population groups were carried out for Germany, Italy and Poland. A new analytical report was published in 2019: the report looked at the 2018 AAI results and trends in AAI over eight years; it also looked into using AAI results for reporting under existing policy frameworks, such as MIPAA/RIS and the European Semester country-specific recommendations (CSRs). The second international seminar took place in 2018. Four national seminars were held (in Italy, Poland, Romania and Spain). In June 2019 the concluding stakeholder meeting was held in Brussels back to back with the final meeting of the Expert Group on AAI.

The project benefited from the advice of the informal Expert Group on AAI that brought together leading researchers, statisticians, government and civil society representatives. The Expert Group met once or twice a year, with email consultations done in between the meetings.