Abstract. The COVID-19 pandemic brought the issue of immigrant irregularity to the public fore, exposing undocumented migrants’ vulnerabilities and the reliance of supply chains on their ‘essential work’. While pro-regularisation instances emerged in several countries, governments responded differently to them. Delving into the political determinants of immigrant regularisation programmes, the article compares the cases of Italy and Spain, traditionally considered as ‘hallmarks’ of the ‘Southern European immigration model’. The findings suggest that the types of actors that mobilised and the arguments they invoked, and governments’ opportunities and constraints in the national and supranational arena were central to explain why Italy approved a collective regularisation and Spain did not.