Public service reform in the shape of collaborative governance is consistently promoted by statutory actors in Scotland and other high-income countries to help develop high-quality and efficient public services, responsive to peoples needs, but this notion contains a number of weaknesses. This chapter explores the potential of the capabilities approach (CA), conversion factors in particular, to achieve a more effective model for conceptualizing, driving and evaluating how public services operate, drawing on empirical work conducted by What Works Scotland. It argues that the CA provides an ethical framework for evaluating the role and function of public services in safeguarding peoples well-being and social justice, especially for those with fewest resources. Employing data from two research projects in areas of multiple deprivation, the impact of public service interventions is evaluated in terms of conversion factors, and how these shape outcomes for citizens and communities. The concept of structural conversion factors is an innovative response to criticism of the CA, and the chapter argues that this modification allows it to better confront the drivers of social injustice.