While global health diplomacy (GHD) has attracted growing attention, accompanied by hopes of its potential to progress global health and/or foreign policy goals, the concept remains imprecise. This paper finds the term has largely been used normatively to describe its expected purpose rather than distinct features. This paper distinguishes between traditional and “new diplomacy”, with the latter defined by its global context, diverse actors and innovative processes. A more concise definition of GHG supports the development of a research agenda for strengthening the evidence base in this rapidly evolving area.