New Public Management has been the prevailing governance model in public sector administration since the late 1980s. In 2005, OECD-DAC member states adopted the resultsbased management model ‘Paris Agenda for Aid Effectiveness’, building on new public management theory and values. The aim was to achieve more effective aid by coordinatingand harmonising donor efforts, aligning development interventions and funding, supporting national ownership and propelling a result- and accountability culture by demonstrating achievements.Despite its worthy ambitions the Aid Effectiveness Agenda has paradoxically failed todeliver on its own outcomes. The results-based management framework underpinning theagenda has proven to be highly complex in methodology, interpretation and application. The framework is laborious and burdensome, diverting time from ‘ordinary’ work and risking a bureaucratization of the development aid sector. The ‘measurement fever’ has grippeddonors and agencies alike, and is now mainly driven by donors’ domestic accountability concerns, rather than the real needs of developing countries. More alarmingly, it has not onlyhad numerous unintended consequences but also outright adverse effects. This in turnen dangers long-term human development.This study sets out to explore to what extent the results-based management framework, based on new public management theory, has been a suitable management model to achieve aid effectiveness in the development aid sector. It departs from the governance theories of Denhardt and Denhardt (2000) and assesses whether New Public Service couldbe a fitting alternative governance model. The study utilizes the realist review methodology,specifically the CMO-configuration, in order to explore how context and mechanisms interact and how this affects the outcome. This study has through its aggregative and configurativeambition explored 26 scholarly articles in the time frame of 2011 to 2021 in order to draw conclusions.The review has found that the results-based management framework does not support the underlying theory of change that is imperative to achieve the Aid Effectiveness Agenda.Contextual factors are found to impede implementation, although due to being under research edit is difficult to determine to what extent. Further, none of the five mechanisms ofthe Paris Declaration can neither fully nor partially be said to contribute to ‘aid effectiveness’as defined in the Aid Effectiveness Agenda. Rather, the review has found that the literatureall point to numerous adverse effects of its implementation.This study concludes that the New Public Service governance model, at least intheory, could prove to be a more suitable management model for the development aidsector. Since the sector is neither linear nor predictable as the business sector for whichthe framework was developed, it is not surprising that adverse effects abound. Especiallysince the development aid sector is highly complex with a multitude of actors, politicalincentives and not least challenging implementational environments. In contrast, New Public Service places the citizen at the centre and aspire at buildingdemocratic citizenship and community through citizen participation and dialogue. Such analternative governance model built on democratic theory and participative epistemologyhas the potential to democratize governance practices by replacing the vertical top-downprincipal-agent dynamics of new public management with more horizontal forms of citizeninvolvement, co-determination and mutual accountability. New Public Service stresses the‘serving not steering’ aspect of governance, which would open up for a more authenticdiscourse of recipients owning development in their own society and setting the direction.No systematic review has previously been carried out to assess governance models inrelation to achieving the Aid Effectiveness Agenda. In fact, there is very little research onwhat has worked or not regarding the agenda. This thesis sets out to fill this gap and tocontribute to the discussion of governance models on a theoretical level. It is also anempirical contribution to applied development management regarding insights about whatcontexts and mechanisms affect aid effectiveness.