The typological, modal, and chemical analyses of the pottery from the Petexbatun region of southwestern Peten, Guatemala, are used to establish a regional ceramic chronology and to assess three theories used to explain the Classic Maya collapse of the ninth and tenth centuries a.d. The three explanations are based on: (1) foreign invasion; (2) commercialization; and (3) internal warfare. Each of these theories suggests different changes in the regional ceramic-production and -exchange systems of the Petexbatun. Shifts in the ceramic production system are monitored using a standardization study, while instrumental neutron-activation analysis (INAA) is used to model changes in interregional exchange. The results of these analyses indicate that there was a continuity in the ceramic assemblage from the Late Classic Nacimiento phase (a.d. 600–830) to the Terminal Classic Sepens phase (a.d. 830–950). Together with little change in architectural, mortuary, and other artifactual styles, this finding suggests that no foreign groups invaded the Petexbatun region, and therefore did not lead to the collapse in the Pasion region. The small decreases in pottery standardization and the minor shifts in interregional exchange do not support the second theory that a major reorganization of Maya economy undercut the power base of the Maya elite class. On the other hand, these small decreases in standardization and in the scale of exchange do support the third theory, which suggests that internal warfare between the regional polities disrupted exchange, leading to more localized production. The stability of the ceramic production and exchange systems in the Petexbatun region throughout the collapse also suggests that the political and economic systems were largely disconnected. These findings suggest that internal political processes leading to an increase in competition and to intensified warfare were important factors in the Classic Maya collapse of the Petexbatun region in Peten, Guatemala.