He was the author or editor of 32 scholarly books and numerous peer-reviewed articles. His most recent research involved three projects: child labor and education policy in India and other developing countries; comparing immigration, refugees and citizenship policies in Japan, Germany, South Africa and the USA; and analyzing the causes and effects of migration and refugee flows. Dr. Weiner's 1991 book The Child and the State in India: Child Labor and Education Policy in Comparative Perspective had a major impact in Indian debates on how to end child labor, and was perhaps his magnum opus. "It was his crowning achievement. It made all of us think about the question of illiteracy," according to Jagdish Bhagwati, a Columbia University economist and colleague since the mid-1950s. Dr. Bhagwati said the book prompted economists to recommend more investments in education for the poor, and policies to help poor people recognize education as a valuable investment. Prior to his book, the prevailing view of many was that countries like India were too poor to do much about child labor or access to education by the poor, because parents needed working-children to support the family and only when incomes rose would this change. Using impassive data and scholarly language, Weiner's work reversed the causal direction, showing that historically and cross-nationally, the reforms which expanded education preceded higher incomes. The 1991 book showed how India had fared worse on illiteracy and education than China. Joshua Cohen said the book had a profound impact in India: "Here was a work, written by a friend of India, which presented irrefutable facts. It presented comparative statistics, and while it raised moral issues, it was not written as a moral diatribe." His contrarian views sometimes caused controversy, e.g., showing that democratization can exacerbate ethnic conflict, or the perverse effects of well-intentioned affirmative-action or child labor policies. With Samuel P. Huntington and Lucian Pye, he was a co-founder and co-director for many years of the Harvard-MIT Joint Seminar on Political Developmentresearch project. Critics associated him, fairly or not, with the Modernizationschool of thought, and with certain US policies during the Vietnam War. His most recent books were The Global Migration Crisis: Challenge to States and to Human Rights ; Threatened Peoples, Threatened Borders: World Migration and US Policy ; The New Geopolitics of Central Asia and its Borderlands ; The State and Social Transformation in Afghanistan, Iran and Pakistan ; and International Migration and Security. Other books include Sons of the Soil: Migration and Ethnic Conflict in India. Among his many former-students are Ashutosh Varshney, and Steven Wilkinson.