Despite significant evidence on the critical role of sensemaking in organisations, our knowledge of the process involved, and how it can be developed and managed in practice, is still considerably under-researched. Through a real-time, mixed-method case study of three Extended Leadership Teams (ELTs) engaging in strategic change, this research identifies specific planning-based practices and parity-based behaviours which underpin the collective sensemaking process. The practices identified include scheduled discourse opportunities, on-going re-alignment and re-prioritisation of strategic activities, and positive positioning of strategy-related time and metrics. The behaviours identified include leader perseverance, aligned signals, mutual trust and middle manager empowerment. Together, they lead to a highly constructive form of collective sensemaking; referred to here as Shared Sensemaking. This research advances sensemaking theory through the development of a process model of Shared Sensemaking and identifying the relationship between this more normative, process