Industry accounts have suggested that growth performance traits and morbidity / mortality may be compromised when pigs are reared in large pen configurations. Therefore, the objective of this study was to determine the effects of small (34 pigs per pen) versus large (272 pigs per pen) pen configurations on the performance, behavior and welfare of the pig during the grow-finish period. Overall pigs in the small pen configuration had better performance measures and improved lesion scores compared to pigs housed in the large pen configuration. The drug cost for small penned pigs was lower, and opening up small to large pens did not adversely affect their resource management behavior. Applying this knowledge to the commercial swine industry may yield several advantages for the producer; including decreased feed costs and fewer days for pigs to reach market weight.