Although pressure ulcers appear to occur infrequently in children, they can have serious consequences such as infection, scarring and changes to body image. This thesis is an account of the development of an instrument to help nurses to identify children most at risk of pressure ulcers, and take preventative action. Prior to 1996, there were very few publications on the problem of pressure ulcers in children; these were mainly anecdotal, or concerned with specialised populations. The main aim of the research presented in this thesis was to develop an evidence-based pressure ulcer risk assessment tool for children. Initially, paediatric pressure ulcer incidence and prevalence studies were carried out at one children's hospital (project 1). This included collecting detailed data on the characteristics of children. The incidence of pressure ulcers in the sample (not including non-blanching erythema) was 3.7%, and the prevalence was 2.2%. A multicentre study was carried out (project 2) in which detailed data of the characteristics of 54 children with pressure ulcers in 11 hospitals were collected. This data set was amalgamated with the data set from project 1. Analysis indicated that the most significant characteristics associated with pressure ulcers were mobility, devices in contact with the skin, anaemia, pyrexia, peripheral perfusion, inadequate nutrition, hypoalbuminaemia, low weight and inappropriate incontinence. These factors were used to develop a pressure ulcer risk assessment (the Glamorgan Scale). An inter-rater agreement study (project 3) was carried out on the Glamorgan scale by collecting 27 sets of paired data. The Glamorgan scale is the first published paediatric pressure ulcer risk assessment scale developed from patient data using statistical analysis. It is being used in paediatric areas in many countries throughout the world, it has been translated into four other languages, and incorporated into paediatric pressure ulcer prevention policies in at least 6 countries.