This study deals with how NGOs make human rights impact assessment in relation to their Rights-Based Approaches (RBAs) and discuss what a common framework for impact assessment could look like. The study deals with Oxfam, CARE and Amnesty International, and analyse how their different backgrounds and approaches influence their work with measuring impact. It is showed that they are not able to link development to human rights and not successful in reporting impact in human rights terms. The NGOs with a background in the development field focus on empowering rights-holders while the NGO with a background in the human rights field focus on duty-bearers. The paper concludes that to be accountable to people in the south NGOs need to co-operate on impact assessment and link it clearly to human rights law. It is important that this is done in a process that empowers partners and rights-holders, rather than reinforces old power structures.