Drivers of outsourcing and influencers of partner selection vary on the basis of the imperatives and strategy of the sponsor organization and what is desired to be outsourced. We outline three key areas of consideration for outsourcing, specifically in the context of outsourcing knowledge-based functions in product development and post-marketing in the areas of safety and risk management, statistics and programming, and scientific writing. We call it “The 3E Principle” which encompasses the “whys” of doing business together. Each company’s priorities differ, and the relative importance of these three principles in partner selection decisions also differs by the function that is being outsourced. The 3Es are Effectiveness, Efficiency, and Economics. Read our published article in Global Forum on The 3E Principle of Outsourcing.