Human-Centred Design approaches in museums give rise to a new, digital cultural heritage design practice by refocusing design from the (digital) technology on to the (digitally-enhanced) visitor experience and requiring involvement in design from both designers and non-designers. This practice is foregrounded as central within a wider landscape of transformative museum design and innovation. The paper calls for a new research agenda that takes design practice as the unit of analysis and recognizes the uniqueness of each cultural heritage organization and its capacity to deploy digital media and technologies successfully in its own unique ways and as a matter of organizational fit. We outline this agenda through a conceptual framework for the analysis of digital cultural heritage design practice along the dimensions of activity, tool mediation, and knowledge production. The framework acknowledges that the design of digitally-enhanced visitor experiences is catalytically mediated by tools and constitutes powerful ways of knowing-in-designing.