User Evaluation of Multi-party Conversational Systems. Recent advances in artificial intelligence, natural language processing, and mobile computing, together with the rising popularity of chat and messaging environments, have enabled a boom in the deployment of interactive systems based on conversation and dialogue. This talk explores the design and evaluation of conversational interfaces, and it is focused on design and evaluation methods which address specific challenges of interfaces based on multi-party dialogue. I will show two projects. First, Café com os Santiagos is an artwork where visitors conversed with three chatbots portraying characters from a book in a scenographic space recreating a 19th-century coffee table. It was accessed by more than 10.000 users in a public space resulting in insights to improve even more the conversation system field. Second, I will show an experiment with a cognitive investment adviser called Finch. Finch interface was able to make a state-of-art artificial conversational governance system accessible for regular users to assist in financial decisions.