While hundreds of Provisional Irish republicans were imprisoned in Portlaoise Prison during the Northern Ireland conflict, their part in the conflict remains largely neglected by researchers. During an attempt to politicise these Provisional IRA prisoners, a cumann (local branch) was formed at a meeting of republicans in Portlaoise in January 1979. In the summer of 1986, four miontuairiscí (minute books) of this cumann were removed from the prison and subsequently hidden by former inmates. These minute books include díospóireachta (debates), tairiscintí (motions), and cláir (programmes). Based on this unique and previously unreleased source, this article evaluates the relationship between Provisional IRA prisoners in the Republic of Ireland and the outside movement during the 1970s and 1980s. By analysing this case study, the article serves two purposes: first, to present the content of these previously unknown notebooks; second, to demonstrates how politically motivated prisoners participate in political debates during confinement.