He is the current Interim Deputy Director General for Science of the International Institute for Applied Systems Analysis (IIASA), as well as the Founding Director of the Wittgenstein Centre for Demography and Global Human Capital – a collaboration between IIASA, the Vienna Institute of Demography (VID) of the Austrian Academy of Sciences, and the University of Vienna.

In October 1985 he joined IIASA to lead the institute’s former World Population Program.

He is also adjunct professor at Shanghai University, where he chairs the international scientific advisory board of the Asian Demographic Research Institute (ADRI).

In 2009, and again in 2016, he received a European Research Council (ERC) Advanced Grant, in 2009 the Mattei Dogan Award of the International Union for the Scientific Study of Population (IUSSP), in 2010 the Wittgenstein Award, (often referred to as "Austria's Nobel Prize"), in 2016 the Mindel C. Sheps Award of the Population Association of America, and in 2023 the Science Prize of the Austrian Research Association.

In 2021 he published “Advanced Introduction to Demography” in which he summarizes the foundations and applications of multi-dimensional demography – a field pioneered by Lutz – which captures population dynamics not only by the conventional age and sex structures, but also by other demographic dimensions such as educational attainment and labor force participation.