There is an increasing need to develop new metrics able to measure organizational performance in the interest of multiple stakeholders in order to improve social and environmental sustainability. These stakeholders could include donors, staff, volunteers, technical experts and the like. It has been argued that it is necessary to take a multi-stakeholder approach in order to find the specific set of indicators within an organization for evaluating comprehensively not only its efficiency but also its effectiveness (Andreaus and Costa, 2014; Arena et al., 2015). However, the use of these multi-stakeholder theories to tailor and apply integrated accounting models in practice has received scant attention. The question that arises is how to develop an accountability theory based in the co-creation of accountability by relevant stakeholders. This study proposes to develop a new accountability framework engaging stakeholders under a post-normal science approach: a co-accountability framework. This study’s contribution is twofold. First, it explores theoretically how post-normal science and multi-stakeholder engagement can help not only to find innovative answers to traditional questions of accountability (for what and to whom?) but also new answers to how and under which consequences accountability is performed. Second, it explores the steps that an organization should take to build up a co-accountability framework co-developed by its relevant stakeholders.