Abstract. How do we construct credible personalities? The current SAL (Sensitive Artificial Listeners) characters were constructed intuitively and can be unconvincing. In addressing these issues, this paper considers a theory of personality and associated emotional traits, and discusses how behaviours associated with personality types in people may be adapted to develop characteristics of virtual agents. Our objective is to ensure that behavioural perceptions of a virtual agent credibly reflect the agent’s ‘actual’ personality as prescribed.