Aims and Objective: To explore differences in nurses' attitudes regarding the importance of family in nursing care and factors associated with nurses' attitudes across 11 European countries. Background: Family involvement in healthcare has received attention in many European healthcare systems. Nurses have a unique opportunity to promote family involvement in healthcare; however, their attitudes and beliefs may facilitate or impede this practice. Design: A cross-sectional survey across European countries. Method: A broad convenience sample of 8112 nurses across 11 European countries was recruited from October 2017 to December 2019. Data were collected using the Families' Importance in Nursing Care-Nurses' Attitudes (FINC-NA) questionnaire. We used the STROBE checklist to report the results. Results: There were significant differences in nurses' attitudes about families' importance in nursing care across Europe. Country was the factor with the strongest association with the total scores of the FINC-NA. Older age, higher level of education, increased years since graduation, having a strategy for the care of families in the workplace, and having experience of illness within one's own family were associated with a higher total FINC-NA score. Being male and working in a hospital or other clinical settings were associated with a lower total FINC-NA score. Conclusion: Nurses' attitudes regarding the importance of family in nursing care vary across 11 European countries. This study highlights multiple factors associated with nurses' attitudes. Further research is necessary to gain a deeper understanding of the reasons for nurses' different attitudes and to develop a strong theoretical framework across Europe to support family involvement in patient care. The inclusion of family healthcare programs in the baccalaureate curriculum may improve nurses' attitudes. Relevance for clinical practice: In clinical practice, the focus should be on identifying influencing factors on nurses' attitudes to enhance families' importance in nursing care across Europe.