Affect is a key factor in human conversation. It allows us to fully understand each other, be socially competent, and show that we care. As such, in order to build conversational interfaces that display credible and expressive behaviors, we should endow them with the capability to recognize, adapt to, and render emotion. In this chapter we explain the background to how emotional aspects and personality are conceptualized in artificial systems and outline the benefits of en-dowing the conversational interface with the ability to recognize and display emotions and personality.