The aim of this study was to explore nurses' attitudes and beliefs about the importance of families in nursing care, as well as the barriers and facilitators within the clinical context that influence the implementation offamily nursing in an in-patient oncology service. A cross-sectional study design, incorporating quantitative and qualitative measurements, was used with a sample of nurses in Spain from an oncology service (N = 39). In general, oncology nurses reported positive attitudes and beliefs about the importance of family in nursing care. However, they did not effectively involve the family in their daily clinical practice. This was due to the nurses' lack of clinical skills and competence to work with families as well as contextual factors such as the lack of time and workload that acted as barriers to the implementation of family-oriented care. This study identified areas of improvement that are needed to promote the effective and sustainable implementation of family nursing knowledge in clinical practice settings.