Over the past decade, several Latin American jurisdictions have extended
rights to sexual minorities. Yet political science attention to this development
has been scant, and scholars know little about the factors that have led
to these unprecedented policy changes. This article fills this gap and explains
policy outcomes in a notoriously understudied policy area by comparing
the two jurisdictions in Latin America that were the first to adopt same-sex
unions: Buenos Aires and Mexico City. The article first argues for the usefulness
of engaging theoretical approaches to the study of social mobilization in
policy analyses. Based on extensive field research, it subsequently advances
the argument that the passage of these pieces of legislation in both cities is
largely the result of the ability of very-well-organized activists to present an
effectively framed policy within rare and favorable political conditions.