Since Outward Bound arrived in the US in the 1960s, it has expanded rapidly and today the group has branches in over 30 nations. The types of people trained in the program have also expanded to include adults, the destitute, the disabled, and entrepreneurs, among others.
外展學校在六○年代傳到美國後開始蓬勃發展，「因為美國的荒野環境更原始、更多元，可將訓練天數拉長，活動設計也更具挑戰，」吳冠璋表示，經過四十多年發展，目前 OB 已在世界三十幾個國家設立分校，訓練對象也擴張到成人、社會邊緣人、身心障礙者、企業界等。