This very idea of “signalling” suggests that the association between skills and formal qualification might be central to how skills are rewarded on the labour market. Less-educated adults are experiencing great difficulties on today’s labour markets across all advanced economies (Abrassart, 2013; Gesthuizen, Solga and KUnster, 2011; OECD, 2016). They face higher risks of unemployment than their better-educated counterparts. When they do find employment, it tends to be in low-status occupations characterised by meagre wages and low job security. Hence, improving the labour market prospects of less-educated adults is a prime challenge for countries that want to maintain social cohesion and avoid excessive social inequalities.