A recommender system has the aim of supporting users at making better choices, by suggesting items that might be interesting for them. The user interface engineering community has a crucial role to make a recommender system more effective. Indeed, on the one hand, a support can be offered to let a user express what she likes and desires at the moment in which the recommendations have to be generated, while on the other hand visualizing and explaining the recommendations to the users can facilitate their acceptance and build trust toward the system. With this workshop, we aim to solicit the collaboration between recommendation and user interface communities, in order to discuss novel ideas for engineering the interaction with Recommenders Systems.