With the start of the great economic recession in 2007, homelessness increased fivefold in some regions of southern Europe. Larger numbers of people experiencing homelessness, compounded by a lowered capacity for social and health services to respond to their needs, precipitated an increase in so-called 'chronic homelessness'. The aim of this study was to establish the presence of chronic homelessness in a defined geographical area of Spain, and to determine the prevalence of diagnosed mental disorders within both the chronic and non-chronic homeless population. A prospective and descriptive study was designed to monitor a cohort of 826 individuals experiencing homelessness who constituted the entire identified homeless population in the relevant territory in 2006. This sample was followed until 2016 and sociodemographic as well as clinical information was collected, including the time spent homeless. The results obtained indicated that one in 10 participants met the criteria for chronic homelessness, a rate that is lower than in the US, where the definition of chronicity that was applied originates from. Alcohol use disorder was the most common mental health disorder that contributed to the chronicity associated with homelessness. Being born in the country (Spain) where the study was conducted and being older were the main other variables associated with chronicity. People defined as chronically homeless in Spain were on average younger than in the US, but women were present in the chronic subgroup at a similar rate. We also reflect on the limitations of the study and in particular the appropriateness of the concept of chronicity as applied to homelessness.