While child protection social workers (CPSWs) make decisions about which children with an injury need a medical examination, we do not know how they make these decisions. We aimed to ascertain the knowledge, attitudes and training of CPSWs in regards to assessing childhood bruising. Paediatricians' views on the bruising knowledge and training of CPSWs were also explored, as well as the relationship and communication between the two professions. ‘Aimed to ascertain the knowledge, attitudes and training of CPSWs in regards to assessing childhood bruising’ Semi‐structured, face‐to‐face interviews were conducted with 39 CPSWs and 16 paediatricians across South Wales and South West England. Interviews were recorded and transcribed until data saturation was reached. Using NVivo, two independent assessors conducted a thematic analysis, identifying themes emerging from the data with group comparisons where appropriate. CPSWs lack confidence in assessing bruising with knowledge gaps regarding bruise patterns and the lack of evidence for ageing bruises. This appears to be linked to an almost complete lack of training. An important theme was that CPSWs regard the clinician's view as paramount, yet paediatricians feel that there is an over‐expectation of what a child protection medical can conclude; this exemplified some of the communication issues between the professions. Evidence‐based training of CPSWs is needed jointly by health and social care professionals, including an understanding of the respective roles. Copyright © 2017 John Wiley & Sons, Ltd. Key Practitioner Messages CPSWs lack confidence in assessing bruising characteristics associated with physical abuse, largely due to their lack of training. CPSWs' decisions to refer for medical examinations are strongly influenced by an exploration of history and key social factors, including chastisement strategies and the home environment. Paediatricians are unaware of CPSWs' training or knowledge, and thus have unrealistic expectations of their assessment of bruising characteristics. Communication between professionals could be improved by joint professional training in this area, providing current scientific evidence relating to bruises and an explicit explanation of the role of each in this assessment. ‘Paediatricians are unaware of CPSWs' training or knowledge, and thus have unrealistic expectations of their assessment of bruising characteristics’