Although the use of temporary agency work (TAW) in firms is heavily debated in the literature, the decision processes and motives behind using or not using TAW are often neglected or only analyzed in rough categories. We address these issues using a theoretical framework for HR outsourcing decisions. Specifically, we ask what triggers the decision about usage of TAW, whether firms have internal alternatives to using TAW, and what their expectations were when they made the decision. We focus on detailed expectations about the effects and analyze how users an d non-users of TAW differ in their respective expectations. Our analyses show that TAW is not a personnel service used by the majority of firms. Besides monetary costs, quality, and flexibility effects, stakeholder and transaction cost effects are relevant for the make-or-buy decisions. Users and non-users of TAW differ significantly in their expectations about some of the effect categories.