What is the source of the Partido dos Trabalhadores’ (PT) success? And is the PT likely to thrive into the future as a key player in Brazil’s party system? In this paper we weigh in on an emerging debate about Lula’s role in the PT’s rise to power. Without Lula’s ability to win more votes than his party, we might not be discussing lulismo at all, much less its difference from petismo. Yet despite Lula’s fame, fortune, and extraordinary political capabilities, lulismo is a comparatively weak psychological phenomenon relative to and independently of petismo. Lulismo mainly reflects positive retrospective evaluations of Lula’s performance in office. To the extent that it indicates anything more, it constitutes an embryonic form of petismo. The ideas that constitute lulismo are similar to the ideas that constitute petismo in voters’ minds, and they have been so since the party’s founding – a nonrevolutionary quest to make Brazilian democracy more equitable and more participatory. Both lulismo and petismo are key sources of the PT’s strength, but petismo is likely to endure long after Lula has departed the political scene.