The study of how and why coalitions are formed has piqued the interest of scholars of parliamentary politics and a cottage industry of research has resulted. Despite the voluminous theories and hypotheses on the ‘why’ and the ‘how’ of coalition formation, current work tends to focus on the role of the large formateur (lead party). In this research we turn our attention to the parties that are being ‘courted’ to join a coalition – the small parties. Why do the small parties join a coalition? Using an experimental cost-benefit model, we examine the factors that influence the decision of small parties to join or not to a join a governing coalition.