Horses were monitored to measure behavioural and physiological stress markers when they were weaned individually in solid partition box stalls or in small groups housed in paddocks. Both treatment groups experienced maternal deprivation stress, but the stalled weanlings had the additive effects of social isolation, which prevented them from performing social behaviors. Weanlings of an average age of 4.5 months were weaned in individual box stalls or in groups of three in a paddock with limited grazing forage and an open shelter available. There were no distinguishable treatment differences between the 11, 17-dioxoandrostanes (indicator of glucocorticoid metabolite concentrations) of fecal samples, either immediately post-weaning or at the end of the 56-day study. All weanlings showed a 4-week post-weaning increase in 11, 17-dioxoandrostanes for reasons that were unclear. The 11, 17-dioxoandrostanes is the metabolite that has been determined to be correlated with plasma cortisol levels, and thus stress levels, in horses. Behavioral observations indicated significant differences in the behavioural time budget of stall-housed and paddock-housed weanlings. Paddock-housed weanlings behaved more like feral horses, spending more time moving and less time lying, and they showed a strong motivation to graze and be near their group mates. Stalled weanlings spent more time engaged in aberrant behaviors such as licking or chewing the stall/shed wall, kicking at the stall/shed wall, pawing, and bucking/rearing bouts. The ability to engage in strongly preferred behaviors, the freedom from aberrant behavior, and the variety of behaviors shown indicated that paddock-reared, group-housed weanlings had better welfare. However, the evidence necessary to conclude that stalled weanlings had poor welfare was insufficient.