At CLEF 2018, the Personalised Information Retrieval Lab (PIR-CLEF 2018) has been conceived to provide an initiative aimed at both providing and critically analysing a new approach to the evaluation of personalization in Information Retrieval (PIR). PIR-CLEF 2018 is the first edition of this Lab after the successful Pilot lab organised at CLEF 2017. PIR CLEF 2018 has provided registered participants with the data sets originally developed for the PIR-CLEF 2017 Pilot task; the data collected are related to real search sessions over a subset of the ClueWeb12 collection, undertaken by 10 users by using a novel methodology. The data were gathered during the search sessions undertaken by 10 volunteer searchers. Activities during these search sessions included relevance assessment of a retrieved documents by the searchers. 16 groups registered to participate at PIR-CLEF 2018 and were provided with the data set to allow them to work on PIR related tasks and to provide feedback about our proposed PIR evaluation methodology with the aim to create an effective evaluation task.