This chapter gives examples how political start-ups gathered momentum and built up critical mass through initiatives like petitions, as Momentum in Hungary did, or a road show, as Nowoczesna in Poland and Progresívne in Slovakia did. It also narrates how data and ideas gathered throughout those initiatives were systematically captured, for example by En Marche in their project “La Grande Marche”. The chapter also highlights how political start-ups like Progresívne in Slovakia, Ciudadanos in Spain or En Marche in France founded themselves, and how they tried to make sure they get the public’s attention with their launch. The chapter then presents how, once the founding is done and basics like a solid core group, a core manifesto and formalities like statutes are in place, political start-ups can get competitive fast. The story of “La Grande Marche”, the innovative early stage of the campaign of Emmanuel Macron, is told in depth. For the project, around 500 field organisers were trained. Altogether, 6000 people participated in La Grande Marche, which became the fundament of the success story that would become Emmanuel Macron and En Marche.