Nowadays, the availability of large collections of data requires techniques and tools capable of linking data together, by retrieving potentially useful relations among them and helping in associating together data representing same or similar real objects. One of the main problems in developing data linking techniques and tools is to understand the quality of the results produced by the matching process. In this paper, we describe the experience of instance matching and data linking evaluation in the context of the Ontology Alignment Evaluation Initiative (IM@OAEI). Our goal is to be able to validate dierent proposed methods, identify most promising techniques and directions for improvement, and, subsequently, guide further research in the area as well as development of robust tools for real-world tasks.