Background: Trauma is a significant public health problem both in the UK and beyond. It can have a devastating impact on individuals, their family and society. The care of injured patients has long been thought to be sub-standard in the UK and patient outcomes were noted to be worse than other developed countries. Between 2010-12 regional trauma systems were introduced in England, with the aim of improving survival and long-term outcomes of injured patients. The aim of this study was to critically assess the implementation of these trauma systems on processes and outcomes of care in two regions of England. Methods: A systematic review was undertaken to identify studies evaluating the association between an inclusive trauma system and patient outcome. A mixed-methods approach was used for the study. Data on trauma deaths were obtained from the UK Office for National Statistics (ONS). The Trauma Audit and Research Network (TARN) database was interrogated to provide data on all patients who presented to hospital within two years before and two years after trauma system implementation. A time-series analysis and a before and after study, using a comparator region to control for temporal trends, was undertaken for each region. Twenty semi-structured interviews with Emergency Department (ED) staff were conducted to gain a broader understanding of the effect of this change. Data were then merged and areas of convergence and discrepancy highlighted. Results: The systematic review identified eight observational studies that all demonstrated a significant fall in the odds of death when patients presenting with traumatic injuries were treated within such a system. However, they were deemed to represent a very low-quality body of evidence. ONS data demonstrated that whilst trauma mortality rates were stable, between 30- 50% die outside of hospital. Analysis of TARN data demonstrated that, following system implementation, a greater proportion of injured patients were seen at Major Trauma Centres (MTCs), quality of care indices such as time to CT scan improved and mortality fell. Analysis of the interviews revealed seven main themes and whilst all staff welcomed the commitment to improve trauma care, some, especially outside of the MTCs, expressed concerns about disengagement and being unable to provide the level of care expected. Conclusions: This study adds to the body of evidence supporting the role of inclusive trauma systems in improving quality of care indices and patient outcomes. Contrary to some other studies, this study has shown improvements within two years, particularly at MTCs. Whilst most ED staff interviewed corroborated this view, some barriers to delivering high quality trauma care were felt to remain. Whilst trauma was once seen as a disease of young men and motor vehicle collisions, it is now dominated by falls in the elderly population and trauma systems must be able to meet their needs. Further research is warranted to learn more about the large population of trauma patients that do not survive to reach hospital. Perhaps some of the greatest future improvements of trauma systems are to be found here.