Social parasites exploit the resources and organization of social insect colonies. There are at least two fundamentally different routes to social parasitism: Social parasites can arise via exploitation of conspecific (or congeneric) social insects, or distantly-related organisms can evolve strategies to exploit social insect colonies. Both types of social parasitism can provide useful insights into cooperation and conflict within insect societies. Closely related social parasites are essentially the outcome of the breakdown of cooperation and the realisation of conflict, and the unique features of their evolution can provide information on how cooperation is normally maintained in insect societies. Distantly related social parasites must evolve de novo exploitation strategies without the benefit of shared ancestry of social traits with their hosts, so that their evolution can be used to examine how cooperation can be exploited independent of these traits. In this presentation I will examine both types of social parasitism in detail, and provide some examples of the insights they can bring to the study of cooperation and conflict.