This study was designed to explore the concept of witnessed resuscitation. This was achieved through a serial approach to conceptually based research that systematically and incrementally developed understanding of the meaning of witnessed resuscitation in the context of emergency resuscitative care for adult victims of cardiorespiratory arrest. Theoretical investigation provided a strong conceptual foundation of existing knowledge and gave direction for further inquiry. Existential investigation comprised a hermeneuticphenomenological study to explore the phenomenon of lay presence during an adult cardiopulmonary resuscitation attempt. Lived-experience material was subjected to thematic analysis and was revealing of five concepts that represented the essential nature of the lived experience. The concept of exposure emerged as the essence of this phenomenon. Research findings derived during theoretical and existential investigation were compared by adapting a method of template comparison. This process culminated in a synthesised conceptualisation of the meaning of witnessed resuscitation of a higher level of abstraction. Ongoing research is needed to determine whether this ‘state of the art’ conceptualisation of witnessed resuscitation holds its boundaries when applied to alternative phenomena, contexts and disciplines. Priority should be given to exploring the application of this concept in the context of patient and family-centred end-of-life care.