Aim: The aim of this study was to report a systematic and psychometric review.

Background: The Nurse Competence Scale is currently the most widely used generic instrument to measure Registered Nurses' competence in different phases of their careers. Based on a decade of research, this review provides a summary of the existing evidence.

Design: A systematic literature review of research evidence and psychometric properties.

Data sources: Nine databases from 2004 - October 2015.

Review methods: We retrieved scientific publications in English and Finnish. Two researchers performed data selection and appraised the methodological quality using the COnsensus-based Standards for the selection of health status Measurement INstruments checklist.

Results: A total of 30 studies reported in 43 publications were included. These consisted of over 11,000 competence assessments. Twenty studies were from Europe and 10 from outside Europe. In addition to experienced nurses, the Nurse Competence Scale has been used for the competence assessment of newly graduated nurses and nursing students, mainly in hospital settings. Length of work experience, age, higher education, permanent employment and participation in educational programmes correlated positively with competence. Variables including empowerment, commitment, practice environment, quality of care and critical thinking were also associated with higher competence. The Nurse Competence Scale has demonstrated good content validity and appropriate internal consistency.

Conclusion: The value of Nurse Competence Scale has been confirmed in determining relationships between background variables and competence. The instrument has been widely used with experienced and newly graduated nurses and their managers. Cross-cultural validation must be continued using rigorous methods.