Social movements and new forms of political organization: Podemos as a hybrid party

In recent years, the restructuring of the party systems in several European countries was ac-companied or preceded by massive waves of anti-austerity protests. Although the causal relation between these mobilizations and the rise of new parties has already been assessed, the organizational features re-main understudied. To fill this gap, here we analyse the impact of the cycle of anti-austerity and pro-real democracy protests which emerged in 2011 with the birth and organizational development of the Spanish party Podemos. Bridging two subfields of social and political sciences-movement studies and party stud-ies-we pay particular attention to the dichotomy between horizontality and verticality within Podemos' organization. In particular, we address the issues of social movement effects as well as party foundation and organizational development. Our main findings suggest that movement mobilization played a large role in shaping Podemos' foundational choices, particularly with reference to the fundamental principles of the party and its strategic positioning. Podemos is also experimenting new democratic methods inter-nally. Nonetheless, empirical analysis shows that, overall, the influence of movements' organizational models on the organizational structure of the party has been limited. Yet, the result is a "hybrid" party that finds a balance between the horizontalism of social movements and the efficiency of parties.