Health professionals working in neonatal and paediatric units are increasingly needing to communicate with patients and patients’ family members in languages other than English. As Australia’s population becomes increasingly diverse, there are higher numbers of people with low English proficiency. Gold Coast Hospital and Health Service must also contend with high rates of tourists, who may also have low English proficiency. Most health professionals must then rely on interpreters – usually hired through formal services, certified by NAATI (in person or via phone). However, bilingual staff, family members, children and even technology such as computers and phones are also used. Little research has investigated the decision-making process used by health professionals when deciding who the most appropriate interpreter is to translate the information they need to communicate in their role. As such, our study aimed to understand the decision-making processes behind a health professional’s assessment of whether patients and their parents need an interpreter and, if so, what type of interpreter is used. Of particular interest was whether there was a relationship between type of information (i.e. medical/non-medical), type of interpreter (i.e. formal/ad hoc), and the HP delivering the communication (i.e. doctor/nurse). Sixty-nine doctors, nurses and allied health practitioners from neonatal and paediatric wards participated in regarding their decision-making about when to use an interpreter, who to use as an interpreter, and barriers to interpreter use. Our results suggested that some health professionals assess whether an interpreter is needed using more heuristic processes or short cuts such as “whether it is their second language”, whether they were “born overseas”, or their appearance. For some, this interacted with a second demographic factor such as their education level or gender. Compared to other health professions, a greater number of nurses reported using heuristics to decide. Other health professionals described using a more systematic approach to their assessment, that considered the verbal and nonverbal behaviour of the parent/s, their level of understanding of English for everyday situations, and their level of understanding of medical jargon. This assessment could involve a small range of behaviours or could be quite complex. The key reason health professionals reported needing interpreters was to ensure patient or parent understanding or comprehension. This was especially the case when the communication was around consent. There was much less discussion about interpreters being needed to (i) ensure communication was two-way, (ii) for parents to ask questions or communicate their views, (iii) for communication about parental involvement in caregiving and (iv) to provide culturally competent care. There was some inconsistency in whether health professionals felt that if one parent spoke English, an interpreter was still warranted for the other parent. There was also a lack of consistency in how health professionals assessed whether there had been ‘sufficient understanding’ of the information provided – or how much was enough for the parent to know. When deciding who to use as interpreters, health professionals described a hierarchical order. Formal interpreters were considered “gold standard”, followed by bilingual staff, family and then children and computer-mediated tools. However, some health professionals expressed a preference for health professionals interpreting rather than formal interpreters. Most health professionals expressed a strong preference for face-to-face interpreters rather than phone interpreters. Health professionals described a number of characteristics that made a family member suitable as an interpreter, including their fluency in English, their relationship with the parent, their age, and their cultural background, which depended on whether they were seen as trustworthy. The majority of health professionals reported that children and computer-mediated tools should not be used, though many reported times when they had or would use them, albeit for simple, day-to-day communication. Health professionals reported difficulties accessing formal interpreters, particularly at night or on weekends. Some staff did not know how to access an interpreter. Health professionals also described a range of problems with the phones used for phone interpreters. Although most actions were in line with current policy related to interpreter use, health professionals were not aware what the policy said. Most assumed there was a policy but had never read it. Moreover, health professionals are clearly making use of interpreters not intended by the policy, including using children under 18 as interpreters.