Review Article Glocalising the theory of generations: The case of Spain Manuela Caballero and Artemio Baigorri Universidad de Extremadura, Spain Abstract This work poses difficulties in the use of the generation concept as a social research instrument, due to its complex and multidimensional nature. A com- plexity by which is not a concept widely used in a current Sociology that focuses more on the mathematisation. But some social processes cannot be reduced to algorithms. For the theoretical review we have used contributions from Sociology, Philosophy and History, because it is of a transversal disciplin- ary nature, and we have applied it to the identification of Spanish generations in the 20th century. Inspired by Ortega’s theses and Strauss and Howe empirical development implemented for American society, the resulting model presents six generations with different collective identities that reflect the social changes in the history of Spain during the last century. A model that, after being tested in sectorial investigations, may constitute a useful new tool for the analysis of social change. Keywords Generation, intergenerational relationships, collective identity, social change Corresponding author: Manuela Caballero, Facultad de CC Econ omicas y Empresariales, Universidad de Extremadura, Avda de Elvas, Badajoz 06006, Spain. Email: manuelacaballero@unex.es Time & Society 0(0) 1–25 ! The Author(s) 2018 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0961463X18783374 journals.sagepub.com/home/tas