Malnutrition is a serious and widespread health problem in community-dwelling older adults who receive care in hospital and at home. Hospital and home care nurses and nursing assistants have a key role in the delivery of high-quality multidisciplinary nutritional care. Nursing nutritional care in current practice, however, is still suboptimal, which impacts its quality and continuity. There appear to be at least two reasons for this. First, there is a lack of evidence for nutritional care interventions to be carried out by nurses. Second, there are several factors, that influence nurses’ and nursing assistants’ current behaviour, such as lack of knowledge, moderate awareness of the importance and neutral attitudes. This results in a lack of attention towards nutritional care. Therefore, there is a need to generate more evidence and to focus on targeting the factors that influence nurses’ and nursing assistants’ current behaviour to eventually promote behaviour change. To increase the likelihood of successfully changing their behaviour, an evidence-based educational intervention is appropriate. This might lead to enhancing nutritional care and positively impact nutritional status, health and well-being of community-dwelling older adults. The general objectives of this thesis are: 1) To understand the current state of evidence regarding nutrition-related interventions and factors that influence current behaviour in nutritional care for older adults provided by hospital and home care nurses and nursing assistants to prevent and treat malnutrition. 2) To develop an educational intervention for hospital and home care nurses and nursing assistants to promote behaviour change by affecting factors that influence current behaviour in nutritional care for older adults and to describe the intervention development and feasibility.