The “large group” concept for pigs is gradually being adopted in North America. Housing grower-finisher pigs in large groups of 50-500 pigs/pen compared to conventional group sizes of 10-40 pigs/pen has the possibility to reduce housing costs and may also simplify some aspects of management. Large group pens prove to be economically attractive to pork producers. However, there is the concern that the social instability of pigs in large groups may lead to poorer growth rates, increased mortality and morbidity, and higher variation in body weights at the end of the production cycle. The goal of this study was to compare production performance of grow-finish pigs housed in large groups (108 pigs/pen) to those housed in conventional groups (18 pigs/pen). It has been suggested that there may be higher levels of undesirable vices such as tail biting, or higher incidence of diseases and mortalities with the formation of pigs into larger groups. However, results from this study do not support this suggestion as similar numbers of pigs were removed from both pen sizes throughout the course of the trial. Pigs housed in the large groups had a lower ADG (2%) than the smaller groups, but there were no significant differences in ADFI and feed efficiency among the two group sizes. Carcass measurements indicated no detrimental effects of either group size. Overall, results indicate that performance in the large groups were not inferior to the smaller groups evaluated in this study.