Modern accounts of Sicilian history in the late fifth century b.c.e. and its relations with Athens often follow Thucydides’ Athenocentric narrative closely, largely ignoring the Sicilian background. This article instead foregrounds the actions and concerns of two important Sicilian cities, Segesta and Leontini, whose perspectives Thucydides chose to leave out or downplay. In particular, Segesta was involved in the complex cross-cultural dynamics of western Sicily, while Leontini demonstrated resilience in its resistance to Syracusan imperialism. Both cities’ relations with Athens emerged from their pre-existing policies and strategies. This article thus develops an alternate narrative of these events that complements Thucydides’ Athenocentric one. To accomplish this, it argues for a more nuanced approach to Thucydides’ narrative: reading it against the grain, supplementing it with data from Diodorus and epigraphy, and placing it in its Sicilian historical and cultural context. In this way, the article develops a new approach to the methodological issues involved in writing the history of poleis that are not emphasized in major extant narrative sources. Recognizing Segesta and Leontini as political actors with their own goals and agendas enables both a new reading of Thucydides and a less Athenocentric account of late fifth-century Sicilian history.