Background: Health professionals working in primary care and public health have opportunities to address bodyweight status issues with their patients through face-to-face contact. The objectives of this all-Ireland project are: 1.to assess the attitudes, current practices/behaviours and knowledge of key health professional groups on bodyweight status; 2. to assess the health professional groups’ ability to identify body weight status in both adults andchildren. The health professional groups are: (a) community related public health nurses; (b) school public healthnurses; (c) GPs and practice nurses (primary care); and (d) occupational health nurses (workplace) from bothNorthern Ireland and the Republic of Ireland.Methods/Design: This all-Ireland multi-disciplinary project follows a mixed methods approach using bothquantitative and qualitative methodologies, and consists of four components:1. Literature review - to explore the role of health professionals in managing obesity through spontaneousintervention in a variety of health promotion settings.2. Telephone interviews and focus groups - to gain an in-depth insight into the views of health professionals inassessing body weight status.3. Survey (primarily online but also paper-based) - to determine the attitudes, current practices/behaviours andknowledge of health professionals in assessing body weight status.4. Online evaluation study - an online interactive programme will be developed to assess health professionals’ability to identify the body weight status of adults and children.Discussion: This project will assess and report the attitudes, current practices/behaviours and knowledge of keyhealth professional groups within Northern Ireland and the Republic of Ireland on body weight status, and theirability to identify body weight status in both adults and children. The results of this project will generaterecommendations for clinical practice in managing obesity, which may inform policy guidelines.