Working Group on Power Sector Restructuring (WGPSR) is the forerunner of IESR.

In 2007, IESR was formally established from the Working Group on Power Sector Restructuring (WGPSR), a working group that was active in 2001–2006. This working group was established in 2001 by International NGO Forum on Indonesian Development (INFID), Indonesia Corruption Watch (ICW), Indonesian Consumer Organization (YLKI), Public Interest Research and Advocacy Center (PIRAC), The Legal Aid Institute (LBH) Jakarta, Debt Watch, and Gemi Nastiti (GENI) Foundation.

WGPSR advocated for electricity sector reform in Indonesia after the financial crisis in 1998 and during the program of structural reforms carried out by the Indonesian government with the support of the IMF and multilateral development banks.

After that, WGPSR was deeply involved in advocating policies and regulations on electricity tariffs, subsidies, and management of the electricity sector. This working group was the first civil society organization to encourage public participation in the formulation of policies and decisions in the Indonesian electricity sector, which at that time was not sufficiently transparent.

Based on the results of an external evaluation conducted in 2006, WGPSR was recommended not only to work in the electricity sector, but to continue working on broader energy issues and their impacts on the environment. In 2007, WGPSR was officially registered as a new organization called the Institute for Essential Services Reform.