One of his main contributions was later called Human Capital Theory, and inspired much work in international development in the 1980s, motivating investments in vocational and technical education by Bretton Woods system International Financial Institutions such as the International Monetary Fund and the World Bank.
Salah satu sumbangan utamanya kemudian disebut Teori Modal Manusia, dan mengilhami banyak karya dalam pembangunan internasional pada tahun 1980-an, memotivasi investasi dalam pendidikan kejuruan dan teknik oleh Lembaga Keuangan Ineternasional Bretton Woods System seperti IMF dan Bank Dunia.