Within the study of travel demand under the activity-based approach (Axhausen and Gärling, 1992; EIRASS, 2004), there has been an increasing interest in the effect of social interactions in activity-travel behaviour (Bhat and Lawton, 2000), and in particular on how social networks influence activity-travel decisions. Complementary, there is a growing interest in the study of social activities, recognising their importance in the overall travel patterns, and their behavioural difference with more studied purposes, such as work and shopping (e.g. Bhat and Gossen, 2004). Despite this interest, an empirical understanding of these two aspects has been limited so far due to the lack of proper data collection efforts that explicitly link travel behaviour and social interactions. Moreover, although data collection and modelling techniques have gone very far understanding individual activity-travel decision making processes in time and space (e.g. Doherty and Miller, 2000), we still know very little about the linkages between social and spatial interactions.