Efforts to reduce adverse event rates in healthcare have revealed the importance of identifying the essential non-technical (cognitive and social) skills for safe and effective performance and developing tools for rating and training those skills. The focus of studies to date has been surgeons, anaesthetists, or the whole team, with less attention paid to other professionals. The aim of the study was to develop a behavioural rating system for non-technical skills of the scrub practitioner (nurse/technician). This paper reports an interview study, as part of a task analysis, to identify the critical non-technical skills for this role, and the development of a prototype behavioural rating system. Experienced scrub practitioners (n = 25) and consultant surgeons (n = 9), from four Scottish teaching hospitals, were interviewed using a semi-structured design. Data that described generic non-technical skills were extracted from the interview transcripts and thereafter, psychologists and panels of perioperative practitioners (n = 4) used an iterative process to develop a skills taxonomy. Three categories of non-technical skills were identified as critical for safe and effective scrub practitioner performance. These were; situation awareness, communication and teamwork, task management. Three underlying skill elements for each of the three categories were labeled by the expert panels and they provided examples of good and poor behaviours for each of these skill elements, drawing on their domain knowledge. The reliability and psychometric properties of the prototype skills taxonomy and behaviour rating system are currently being tested using standardized, simulated scenarios.