A new breed of IT service providers, termed Application Service Providers (ASPs), has emerged during the last several years. While the ASP paradigm is opening new options for strategic governance of organizational IT infrastructures, implementation of this model is fraught with several uncertainties. This chapter describes a particular type of uncertainty, termed the “know-what” uncertainty, that firms generally face as they implement any techno-organizational innovation, and discusses some specific know-what uncertainties associated with the client adoption of the ASP paradigm. The chapter then discusses the role that participation and trust (in the ASP organizing vision) play in mitigating the client-side know-what uncertainties during the course of adoption and implementation of this new IT governance model. The chapter also provides some recommendations for clients and vendors for making this new IT services paradigm a successful reality.