The current estimate of live-born piglet pre-weaning mortality in UK outdoor systems is 11% (MLC, 2006), representing a major welfare and economic concern. The majority of deaths occur in the first few days of life when the piglets are at their most vulnerable. Selecting for high survival in piglets, may allow breeding of animals better able to survive and better suited to alternative and less restrictive systems than the farrowing crate. The aim was to develop and measure behavioural and physiological indicators of neonatal survival, and to determine treatment effects in populations of piglets selected for high survival and control lines farrowing in an outdoor system.