In this paper, we examine a particular form of social network which we call a friendship-event network. A friendship-event network captures both the friendship relationship among a set of actors, and also the organizer and participation relationships of actors in a series of events. Within these networks, we formulate the notion of social capital based on the actor-organizer friendship relationship and the notion of benefit, based on event participation. We investigate appropriate definitions for the social capital of both a single actor and a collection of actors. We ground these definitions in a real-world example of academic collaboration networks, where the actors are researchers, the friendships are collaborations, the events are conferences, the organizers are program committee members and the participants are conference authors. We show that our definitions of capital and benefit capture interesting qualitative properties of event series. In addition, we show that social capital is a better publication predictor than publication history.