This PhD by publication explores how ‘knowledges’ in social work research are authorized often to those who use and provide services. It draws together 11 publications, which are a mixture of sole and co authored peer reviewed journal articles, book chapters, and co authored publications for a range of charitable and public bodies both within the UK and Europe. The concept of ‘epistemic injustice’, is used to examine the connections between my published works. Stemming from the tradition of feminist philosophy, epistemic injustice is when the capacity to hear another’s testimony is diminished. With its focus on the interrelationship between hearing and being heard, epistemic justice has an under utilised value in social work practice and research. Building on the central themes of voice and justice, I argue that the discrediting of an individual testimony leads to individual and collective harm, as the opportunities for some to contribute to the common store of social meanings are diminished, including asylum seeking young people, victim and survivors of child sexual exploitation, child sexual abuse and child trafficking. My published works are examined as case studies to consider which and whose knowledge is taken seriously and why. I considers the harms done through the process of being discredited; both to the individual (their testimony and their identity –as sense of self is shaped by these negative associations) and to a developing knowledge (as accounts are missed and the potential growth of connections (be they defeating, justifying or inferential) is lost. Although all knowledge is partial and co-produced, I consider the obligation to make relevant efforts to understand how the world looks from different points of view, especially those who use and provide services.