Patients with disc displacement without reduction (DDwoR) may suffer sudden-onset painful/limited mouth opening and immediately seek care from clinicians at the frontline. Currently, there is a lack of understanding of frontline, and specialist, clinicians' decision-making processes when encounter DDwoR patients. Understanding these processes and what influences them is an essential first-step towards the development of an evidence-informed behavioural intervention to improve first-line care of DDwoR patients. The objective of this study was to examine clinicians' decision-making processes in managing DDwoR and influences upon them. A qualitative study informed by the Theoretical behaviour change Domains Framework (TDF) was conducted. The TDF-based topic guide was utilised in semi-structured interviews with a purposive sample of medical and dental frontline and specialist clinicians who might encounter patients with DDwoR. Interviews continued until data saturation across the theoretical domains was achieved (n = 21) and were analysed using the TDF to structure coding alongside framework analysis. The results highlighted the complexity of decision-making process and demonstrated the influences of all the domains on clinicians' decisions. Of the influential factors identified, the frontline clinicians placed most emphasis on their lack of: 'knowledge', 'skills', and 'experience' with DDwoR management. The clinicians at the frontline showed high degree of diagnostic and management uncertainty and preferred to refer DDwoR patients early. The frontline clinicians displayed lack of knowledge, experience, and training to diagnose and treat DDwoR. There is a need to enhance the clinicians' knowledge and skills in managing DDwoR at the first-point of contact. The frontline clinicians showed unfamiliarity with DDwoR presentation and inability to diagnose and, consequently, treat DDwoR. This indicates that DDwoR patients may, currently, receive sub-optimal first-line care in the UK. Designing a behaviour change intervention informed by the identified theoretical domains can support the clinicians' decisions and improve patients' care. Copyright © 2019 Elsevier Ltd. All rights reserved.