Among the private diaries of Vatican ii, those of Yves M.J. Congar (1904-95) and Henri de Lubac (1896-1991) are undoubtedly the most important. The aim of this article is to assess the significance of Congar's My Journal of the Council in order to draw attention to its significant influence in the on-going reception of the Vatican ii, and to the perennial challenge of reform in the Church. Congar was one of the most prominent of the ressourcement theologians, associated principally with the Jesuits of Lyon-Fourvière and the Dominicans of Le Saulchoir, Paris. Their influence pervaded French society and theology in the period 1930-1960, and beyond, and inspired a renaissance in Catholic thought. The article assesses Congar's role in that renaissance, as well as his immense participation in the elaborate work of the Council, not least his involvement with the Belgian theologians with whom he formed a strategic liaison. Among the private diaries of Vatican ii, those of Yves M.J. Congar (1904-95) and Henri de Lubac (1896-1991) are undoubtedly the most important. The aim of this article is to assess the significance of Congar's My Journal of the Council in order to draw attention to its significant influence in the on-going reception of the Vatican ii, and to the perennial challenge of reform in the Church. Congar was one of the most prominent of the ressourcement theologians, associated principally with the Jesuits of Lyon-Fourvière and the Dominicans of Le Saulchoir, Paris. Their influence pervaded French society and theology in the period 1930-1960, and beyond, and inspired a renaissance in Catholic thought. The article assesses Congar's role in that renaissance, as well as his immense participation in the elaborate work of the Council, not least his involvement with the Belgian theologians with whom he formed a strategic liaison.