The measurement of port performance is relevant for port users, policy makers, port developers and other stakeholders. This paper describes the development of one port performance indicator: intermodal connectivity. Intermodal connectivity is relevant, as many port authorities as well as policymakers have the ambition to handle a larger share of the volumes with intermodal transport. A higher share of intermodal transport requires a better connectivity between ports and intermodal terminals in the hinterland. This paper presents two intermodal connectivity indicators, one for a specific port and one for as group of ports. At least in Europe, reliable data on intermodal services is not publicly available. Thus, we developed an intermodal connectivity indicator based on data provided by individual ports. 26 ports provided data, these ports handle roughly 70% of all container volumes. The data for 2010 and 2011 suggest that the intermodal connectivity of the EU has increased in 2011. We finalize the paper with conclusions and future research options to further advance this indicator.