Although the role of local Human Rights Organizations (HROs) has attracted some attention in the transitional justice literature, this note from the field examines an under-studied HRO strategy: the production and systematization of information. In particular, it focuses on the Center for Legal and Social Studies’ (CELS) efforts to promote accountability for the gross human rights violations committed during Argentina’s last period of military rule (1976–1983). It argues that the production and systematization of information is foundational for transitional justice advocacy, and CELS’ work has influenced Argentina’s transitional justice processes and the broader struggle for accountability. The main focus of the note is the use of information for post-transition legal accountability, the purpose of which is to set judging standards and point out difficulties in prosecuting systematic human rights violations. This is addressed by describing a specific information strategy implemented by CELS. This information deals with the status of trials for past human rights violations ongoing throughout Argentina.