Strategic alignment between business and IT is known to be important for achieving good business performance in one organization. It is not clear how strategic alignment influences the performance of a business network consisting of multiple organizations. This paper presents a method to assess inter-organizational Extended Strategic Alignment (ESA) based on the analysis of inter-organizational alignment processes consisting of drivers, levers, and impacts. The method is applied to a large e-government network for social security in the Netherlands between 2002 and 2006. Six examples of ESA were found, all being very complex and time-consuming sequences of activities. Six years after the government decision to implement the new Social Security Act, none of the six ESA examples has resulted in significant improvement of business or IT performance.