Résumé : This paper studies the co-evolution of firm boundaries and capabilities by examining the influence and interplay of process commoditization, changing external availability of capabilities and firm specific paths of governance decisions, along with strategic drivers guiding these decisions. We test hypotheses on a unique and comprehensive panel of global services sourcing projects from early experiments in 1980s through 2011. Our findings suggest that initial firm governance decisions are strongly influenced by process commoditization, external availability of services, and firm strategic objectives. With experience, governance decisions are primarily affected by past decisions and emerging – internal and/or external – sourcing capabilities. The results indicate persistent heterogeneity of boundary configurations as firm and supplier capabilities develop and differentiate over time.