This paper describes a study of the effects of two acts of social intelligence, namely mimicry and social praise, when used by an artificial social agent. An experiment (N = 50) is described which shows that social praise—positive feedback about the ongoing conversation—increases the perceived friendliness of a chat-robot. Mimicry—displaying matching behavior—enhances the perceived intelligence of the robot. We advice designers to incorporate both mimicry and social praise when their system needs to function as a social actor. Different ways of implementing mimicry and praise by artificial social actors in an ambient persuasive scenario are discussed.