Although advances have been made in facilitating the implementation of evidence-based treatments, little is known about the most effective way to sustain their use over time. The current study examined the sustainability of one evidence-based treatment, Parent-Child Interaction Therapy (PCIT), following a statewide implementation trial testing three training methods: Cascading Model, Learning Collaborative, and Distance Education. Participants included 100 clinicians and 50 administrators from 50 organizations across Pennsylvania. Clinicians and administrators reported on sustainability at 24-months, as measured by the number of clients receiving PCIT and the continued use of the PCIT protocol. Multi-level path analysis was utilized to examine the role of training on sustainability. Clinicians and administrators reported high levels of sustainability at 24-months. Clinicians in the Cascading Model reported greater average PCIT caseloads at 24-months, whereas clinicians in the Learning Collaborative reported greater full use of the PCIT protocol at 24-months. Attending consultation calls was associated with delivering PCIT to fewer families. Implications for the sustainable delivery of PCIT beyond the training year as well as for the broader field of implementation science are discussed.