How people's feelings and interpersonal behaviour change across time can be represented as movements within a core affect and an interpersonal space. To gain insight into the relationship between affect and behaviour dynamics, the present study examined how individual differences in intraindividual variability in core affect relate to those in interpersonal behaviour, and how both are related to personality traits. In an experience sampling study, 63 participants were asked to monitor their core affect during one week and their interpersonal behaviour during another one. The results demonstrated a fairly consistent correspondence between several indices of people's variability in core affect and interpersonal behaviour, indicating that emotional lability also signals behavioural volatility and vice versa. Copyright © 2010 John Wiley & Sons, Ltd.