Project management is a complex process involving different stakeholders within and outside the firm. These stakeholders involve among others, the client who has the initial need, and establishes the project requirements and boundaries; the sales teams involved in developing the initial solution and sealing the contract with the client; the project management practitioners responsible for executing the solution as per the contractual requirements; different organizational units, such as engineering, finance, supply chain, health, and safety; and other stakeholders, such as sub-suppliers, legal authorities, consultants, and funding agencies. These stakeholders have different perspectives and objectives that make project management a complex process. In this chapter the challenges, benefits, and opportunities of inter-organizational integration, transition, and collaboration within and between firms in large complex projects are explored. The scope of this chapter is on the interface between the sales front-end phase and the project initiation phase because it is in the sales front-end, where the strategic and operational direction for the rest of the project is set and agreed. A better understanding of this interface may provide opportunities for improvement in project management success.