A significant part of the interaction between journalists and their sources in political journalism is informal or not mentioned in the media content. Visibility/invisibility and formality/informality are tactical choices applied by journalists and sources. They influence agenda building in the short term and shared interpretations that dominate the public sphere in the long term.However, the extent to which informal and/or invisible sources participate, what their role is, and why have not been consistently measured. This paper offers a matrix model to map and compare the usage of formal/informal and visible/invisible interactions between journalists and their sources. The data consists of 475 journalist-source interactions in Lithuania and Sweden reconstructed by 33 political journalists.The results demonstrate how different interactions presuppose different source roles in the news process. Formal invisible sources act as gatekeepers, and informal invisible sources act as agenda setters.