Born in Philadelphia, Pennsylvania. Sailer received a Christian education since his youth. He graduated from Princeton University in 1919 and was president of the Student Volunteer Band. He obtained a master's degree from Columbia University in 1922 and a doctorate the following year. At the same time, he took courses at Union Theological Seminary, New York. He came to China in 1923 and taught in Yenching University. He had been dean of the Psychology and education departments.
Sailer served as chairman of Yenching University Christian Fellowship for many years and supported students who had financial difficulty by his own means. During the Sino-Japanese War, members of anti-Japanese organizations frequently took cover in his residence. During the civil war in China, he helped those students who supported the Communist Party escape from the Nationalist Party's persecution and helped them in transporting medicine to the Liberated Area.
In 1951 Sailer left China and returned to the United States. In later years he taught in Pakistan at Forman Christian College. He retired in 1963. In 1973 he was invited to China for an official visit and was welcomed officially by the government. Zhou En Lai commended him as a "friend of the Chinese people." After he returned to the United States, he wrote an article, "Ten Suggestions for Working to Understand China and America Better," and served as resident of the Washington America-China Friendship Association. After his death, Beijing University held a memorial service in his honor. Both the China Daily and Beijing Weekly ran articles in remembrance of Sailer.