Income and earning inequality has been on the rise in most of the OECD and in many emerging economies since the 1980s. This paper estimates a model of earnings inequality across OECD countries that incorporates determinants of relative demand and supply of more and less-skilled labour. Drawing on OECD data we find that skill-biased technological change – measured as a common cross-country time trend and the level of multi factor productivity – has been the key driver in increasing earning differentials. The analysis also shows that educational attainment has mitigated the impact of skill-biased technological change on earning differentials, but has in most countries been unable to fully compensate. In line with previous OECD analysis, changes in structural policies and labour market institutions, such as deregulation of product and labour markets have exerted upward pressure on inequality. The estimated model is used to decompose historical changes in earning differentials and to construct forward looking scenarios up to 2060. If the common cross-country trend of skill-biased technological change observed during the last 25 years prevails, earning differentials will on average increase by almost 30% in the OECD by 2060. Finally, the model is used to simulate the consequences of alternative policy scenarios over the coming 50 years.