Journalism is one of many institutions dealing with transgressions at a societal level. This dissertation is partly about how it has come to occupy that position, but foremost about how practicing that mission constructs and defines journalism as a social institution and constructs identity, legitimacy and power. The object of study is one of the most high-profile programs of investigative television journalism in Sweden, Uppdrag granskning (Mission Investigate), which is analyzed as an instrumental case study.A quantitative content analysis of all 1,034 of Uppdrag granskning’s episodes broadcast between 2001-2014 shows that the public sector is more investigated than the private, and that Vård och omsorg (social care), Ordningsmakt (society monitoring power) and Handel och industri (trade and industry) are the most frequently investigated fields. Whereas the fields of Media (media), Kultur (culture) and Genus (gender) are fields investigated to a minor degree. Politicians and other public officials are more often the objects of investigation than other professional groups. A narrative analysis of five episodes shows how investigations construct journalism’s institutional identity, and reproduce and legitimize journalistic power when presented in the form of a legal narrative. The dissertation also features results of an interview study with five of Uppdrag granskning’s journalists. They give their own perspectives and reflections about investigative journalism and power.The results of the qualitative analysis show how the examined episodes of Uppdrag granskning construct journalism as an institution that: (1) identifies what is wrong in society, and who is responsible, (2) acts as a constructor and guardian of societal moral, (3) interacts in an intricate way with the formal legal system, investigating it, collaborating with it andsometimes stepping in where it fails, (4) exercises a form of justice that is mainly retributive towards those investigated, serves to restitute victims and by means of an emotional focus endeavors to engage and activate viewers’ sense of justice, (5) justifies means of deception and deceit to expose wrongdoing, (6) faces the creative challenge of shouldering the journalistic mission to investigate in a just and fair way, while at the same time making sure the investigations are dramatic and interesting enough to be worth watching on prime time television.