Chickens can differentiate between cagemates and strangers and they are often exposed to unfamiliar birds in novel environments under modern farming practice; this can lead to xenophobia, aggression and distress (Rajecki et al., 1976; Jones, 1996). Chickens form olfactory memories and regulate their behaviour in response to naturally occurring and artificial odours (Jones & Roper, 1997). The presence of a familiar odourant (vanillin) increased social dispersal and feeding when familiar pairs of chicks from the same cage were tested in a novel environment (Jones et al., 2001); suggesting that familiar odourants can be reassuring. Here, we asked if the presence of a familiar odour (vanillin) would increase social affiliation when two unfamiliar pairs of chicks were placed in a novel test arena.