‘Contagion theory’ is one of the most appealing explanations of women’s representation in national legislatures. The process of contagion operates both at the party-system level, ‘macro-contagion’, and at the district level, ‘micro-contagion’. PR electoral systems are found to be more conducive to contagion than SMD systems (Matland & Studlar 1996). Yet, while PR systems achieve higher levels of women’s representation they also present the largest variance. By examining the impact of contagion at the district-level over a three-decade period in Spain and Portugal –two countries with similar political culture, electoral system and timing of quota adoption– we refine the basic tenets of ‘micro-contagion’ and show that the nomination of more women candidates in party lists does not follow an imitative strategy but it is rather stimulated by party organizational factors and constrained by party magnitude, which follows a non-linear trend over time.
