[2] His area of expertise is East Asia;[3] while in the Foreign Service, he was stationed in Taiwan (the Republic of China), the Republic of (South) Vietnam, and Washington, D.C.. After leaving the State Department in 1965, he received his PhD degree in East Asian studies at Georgetown University.
While at Penn State, Duiker served for ten years as Director of International Programs and as Chairman of the East Asian Studies Committee.
[4] The last, published in 2000, was the first comprehensive biography of Ho Chi Minh using sources from Vietnam.
He also collaborates with his colleague Jackson J. Spielvogel in authoring the textbook World History, which is now in its ninth edition with Cengage Press.
He is also the sole author of Contemporary World History (Cengage Press), which is now in its seventh edition.