Social motivation (as measured by a visually isolated chick's tendency to establish visual contact with, move towards and remain in proximity to a group of conspecifics) was assessed in lines of Japanese quail which had been selected for high (HSR line) or low (LSR line) levels of an index of treadmill behaviour which combined the tendency to run towards conspecifics with the tendency to move away from them. HSR line chicks peeded sooner and more frequently before establishing visual contact with conspecifics and spent more time close to conspecifics after visual contact had been established than LSR line chicks. HSR line chicks also tended to have shorter latencies to establish visual contact with conspecifics, jump more and interact more with conspecifics than LSR chicks. It is suggested that these results indicate that selection for treadmill behaviour, which is considered to be a measure of social reinstatement tendencies, has influenced overall levels of social motivation. Furthermore, it would also appear that the phenotypic differences between the HSR and LSR lines are relatively intensive to genotype x environment interactions.