Social scientists call Matthew eeect the self-reinforcing mechanisms whereby initially small advantages accrued by individuals, e.g. in reputation, capital, or access to opportunities, beget further advantage and result in growing inequality. While there is extensive literature on the Matthew eeect, the notion has not been explicitly deened. In this paper, we take a rst step in this direction by providing a formalisation of Matthew eeects within the framework of team semantics, and by introducing a logic for analysing the properties of the dependence relations involved in Matthew eeects. We also show via an example how to use this logic to formalise a statistical analysis of a Matthew eeect.