Proportionality analysis is considered a central tool for rights adjudication in contemporary constitutional law. Prevailing academic narrative explains its worldwide spread as a matter of legal migration. This chapter challenges this narrative through the analysis of Argentine constitutional practice. It reconstructs the different variants of proportionality scrutiny that have been applied by the Argentinian Supreme Court from the beginnings of the twentieth century, well before the development of the modern proportionality test by the German Constitutional Court, and surveys its role in the adjudication not only of civil and political rights but also social rights. It ultimately argues that constitutional practices in this domain are better explained under a paradigm of interaction, rather than under one of migration.