Despite the growing importance of the Accountability for Reasonableness (A4R) framework in priority
setting worldwide, there is still an inadequate understanding of the processes and mechanisms underlying its
influence on legitimacy and fairness, as conceived and reflected in service management processes and outcomes.
As a result, the ability to draw scientifically sound lessons for the application of the framework to services and
interventions is limited. This paper evaluates the experiences of implementing the A4R approach in Mbarali District,
Tanzania, in order to find out how the innovation was shaped, enabled, and constrained by the interaction
between contexts, mechanisms and outcomes