Staged adoption models are a common feature of information systems (IS) adoption literature, yet these are rarely used in open source software (OSS) adoption studies. In this paper, a staged model for classifying the organizational adoption of OSS is proposed, based upon a critical review of existing staged adoption models and factors identified from OSS adoption literature. Innovations in the proposed model include: defined transition pathways between stages, additional stages and a decomposition of cessation of use into four distinct pathways.