The ongoing success of e-partnership requires the constant monitoring and measuring of its progress and outcomes. Many companies rushed into e-partnerships in order to exploit complementary resources that they lacked but knew little about how to make their partnerships work and how to effectively monitor and measure its performance. Even today, many partnerships are left to drift without a system in place to assess the quality of partnerships. So, how can the productivity and health of a partnership be monitored and measured? The biggest challenge relating to performance measurement for e-partnerships is that e-partners are often independent business firms and legal entities with different stakeholders and different business objectives and goals. In the supplychain, for example, one firm can rarely control the entire supply chain’s performance. However, performance measures that can be extended across firm boundaries and processes are needed to measure inter-organizational e-partnerships. The uncertainty and intangibility of e-business and information technology add more complexity and challenges to the measurement of e-partnership performance. Looking at the current literature, it is not hard to find that the development and implementation of performance measurement systems for inter-firm collaboration is still in its infancy. Overall, traditional performance measures do not focus on key inter-firm activities to monitor extended enterprise performance. This chapter reviews and discusses various concepts, models and issues of performance measurement. On the basis of that, the chapter proposes, by taking a balanced scorecard approach, a new set of performance metrics for managers to assess the process and outcome of e-partnerships in a comprehensive manner. The chapter will also help e-partners to benchmark against best practices and determine future direction and priorities in their e-business partnerships.