To this end, we examine the productivity impacts of IT outsourcing in a sample of large U.S. firms. Consistent with the widely accepted definition of IT outsourcing in academia and practice (Gurbaxani 2007; Young 2004), we consider only multiyear contractual arrangements in which a vendor manages part or all of a client’s IT operations. We begin our analysis with a matching technique based on propensity scores (Heckman et al. 1998; Rosenbaum and Rubin 1983) and examine the productivity gains for outsourcing firms relative to their counterfactuals (controlling for potential endogeneity). We complement this approach with switching regression which allows us to compare the productivity gains for firms that have จัดจ้างคนภายนอก with the hypothetical gains in the alternative sourcing mode. Since firms choose their mode of services delivery, we incorporate a firm’s self-selection process into the estimation procedure to control for potential bias. The resulting selection equation enables us to identify key factors that increase a firm’s propensity for outsourcing and helps to establish the direction of causality from outsourcing to productivity gains. These factors include a firm’s efficiency level, its financial leverage, variability in its business conditions, and its IT intensity.