In many parts of the world, recognition of prior learning (RPL) is considered to be an important means of improving access to VET qualifications. In Switzerland -- the country with arguably the highest rates of company-based VET at upper secondary level -- adults with work experience of at least 5 years have had the option of accessing VET qualifications at the upper secondary level through RPL for more than 10 years now. Still, today, only roughly 6 percent of adults (over 25 years) who achieve a VET qualification make use of that option. The rest either pursue a regular VET programme, or at least take the ordinary final VET exam. This article discusses the reasons underlying this slow rate of RPL expansion in Switzerland. Arguing from a historical-institutionalist perspective, the article shows how the institutional framework of mainly company-based Swiss VET and the underlying actor coalition pose substantial barriers to the expansion of RPL. Nevertheless, by comparing different rates of RPL uptake across a range of economic sectors and different parts of the country, this article brings to light some key factors that promote the expansion of RPL.