Aims: To explore adult Emergency Department patient experiences to inform the development of a new Emergency Department patient-reported experience measure. Design: Descriptive, exploratory qualitative study using semi-structured individual interviews with adult Emergency Department patients. Methodology: Participants were recruited across two Emergency Departments in Southeast Queensland, Australia during September and October 2020. Purposive sampling based on maximum variation was used. Participants were recruited during their Emergency Department presentation and interviewed in 2-weeks via telephone. Inductive thematic analysis followed the approach proposed by Braun and Clarke (2012). Results: Thirty participants were interviewed, and four themes were inductively identified: Caring relationships between patients and Emergency Department care providers; Being in the Emergency Department environment; Variations in waiting for care; and Having a companion in the Emergency Department. Caring relationships between patients and Emergency Department care providers included being treated like a person and being cared for, being informed about and included in care, and feeling confident in care providers. Being in the Emergency Department environment included being around other patients, feeling comfortable and having privacy. Variations in waiting for care included expecting a longer wait, waiting throughout the Emergency Department journey and receiving timely care. Having a companion in the Emergency Department included not feeling alone, and observing care providers engage with companions. Conclusion: Patient experiences in the Emergency Department are multifaceted, and themes are not mutually exclusive. These findings demonstrate consistency with the core experiential themes identified in the international literature. Impact: Strategies to improve patient engagement in shared decision-making, and communication between patients and care providers about wait times will be critical to optimizing Emergency Department patient experiences, and person-centred practice. These findings holistically conceptualize patient experiences in the Emergency | 3331 BULL et aL. 1 | INTRODUC TI ON Patient experiences--a description of what happened during a care encounter, and how it happened from the patients' perspective (Bull et al., 2019)--are unique and complex in the Emergency Department. A recent review identified that Emergency Department patient experiences can be broadly described by two interrelated themes: Relationships between Emergency Department patients and care providers, and Spending time in the Emergency Department environment (Bull et al., 2021). Other reviews have similarly demonstrated growing interest in this area by describing the determinants of patient experiences in the Emergency Department including, staff-patient interactions (particularly related to communication and empathic care), wait times, the Emergency Department environment and the emotional impact of experiencing an emergency (Gordon et al., 2010...