Which new parties entered national parliaments in advanced democracies over the last four decades and how did they perform after their national breakthrough? This article argues that distinguishing two types of party formation (that facilitate or complicate party institutionalisation) helps to explain why some entries flourish, while others vanish quickly from the national stage. New parties formed by individual entrepreneurs that cannot rely on ties to already organised groups are less likely to get reelected to parliament after breakthrough than rooted newcomers. This hypothesis is tested on a newly compiled dataset of new parties that entered parliaments in 17 advanced democracies from 1968 onwards. Applying multilevel analyses, the factors that shape newcomers' capacity to reenter parliament after breakthrough are assessed. Five factors have significant effects, yet affect party performance only in particular phases: both a party's electoral support at breakthrough and its operation in a system with a strong regional tier increase the likelihood of initial reelection. In contrast, a distinct programmatic profile, the permissiveness of the electoral system and easy access to free broadcasting increase a party's chance of repeated reelection. Only formation type significantly affects both phases and does so most strongly, substantiating the theoretical approach used in this article.