Staging models in medicine aim to delineate disease progression and help choose effective treatments and make a reliable prognosis. In psychiatry, staging is still preliminary, given the difficult delineation between disorders and the lack of known pathophysiological underpinnings. Still, trans-diagnostic as well as disorder-specific staging models for illness progression in psychiatry have been proposed. This chapter presents the state of the art with regard to staging models of bipolar disorder and the clinical and research evidence for episode recurrence, inter-episodic functional impairment, and cognitive dysfunction as determinants of illness progression.