In 1898, at the age of 23, he was selected due to his education to be trained in the United States as a missionary. On July 10, 1898, Aggrey agreed and left the Gold Coast for the United States, where he settled in Salisbury, North Carolina, and attended Livingstone College. He studied a variety of subjects at the university, including chemistry, physics, logic, economics and politics. In May 1902 he graduated from the university with three academic degrees. Aggrey was very talented in language and was said to have spoken (beside English) French, German, Ancient and Modern Greek, and Latin.