The history of juvenile institutions has usually been described from the perspective of officials. By offering a microhistorical view to the lives and reasoning of girls and young women labelled as "disorderly" or "wayward" and placed at reformatory, this paper aims at a close examination of the reform school education for delinquent girls in the beginning of the 20th century. The paper is based on a unique archive-source, letters and hand-written and -illustrated newspapers composed by the girls in a Finnish reform school for delinquent girls, "Vuorela" (founded 1893). The texts are approached from two perspectives: as autobiographical narratives, in which the girls' construct their identities by writing, and on the other hand as instruments used for institution's educational purposes, reflecting the voices of the personnel. In the reformatory even letter writing served the goal of moulding the girls into an acceptable female adulthood. In their letters and stories the girls present illumining narratives of themselves as offenders: fallen, penitent or incorrigible etc. Expectations concerning female behaviour and procedures through which the institution aimed at reshaping the girls' identities along acceptable guidelines are present in the ways the girls expressed themselves and it is this very process that I am focusing on in my presentation.