The WHO-5 Well-Being Index is a 5-item questionnaire assessing subjective psychological well-being. It was developed from the WHO-10 and has been translated into over 30 languages. A systematic review of the literature found that the WHO-5 has high clinimetric validity, is sensitive and specific for depression screening, and is applicable across various study fields. It is a short, non-invasive tool that measures well-being and has been used in clinical trials to assess treatment outcomes. The WHO-5 has been validated in multiple studies, showing good performance in detecting depression with a cut-off score of ≤50. It is also applicable in various fields such as diabetes, alcoholism, cardiovascular disease, neurology, and stress research. The WHO-5 is a reliable and valid tool for assessing well-being and has been successfully used in both clinical practice and research. The review concludes that the WHO-5 is a highly useful tool for screening depression and assessing well-being across different populations and settings.The WHO-5 Well-Being Index is a 5-item questionnaire assessing subjective psychological well-being. It was developed from the WHO-10 and has been translated into over 30 languages. A systematic review of the literature found that the WHO-5 has high clinimetric validity, is sensitive and specific for depression screening, and is applicable across various study fields. It is a short, non-invasive tool that measures well-being and has been used in clinical trials to assess treatment outcomes. The WHO-5 has been validated in multiple studies, showing good performance in detecting depression with a cut-off score of ≤50. It is also applicable in various fields such as diabetes, alcoholism, cardiovascular disease, neurology, and stress research. The WHO-5 is a reliable and valid tool for assessing well-being and has been successfully used in both clinical practice and research. The review concludes that the WHO-5 is a highly useful tool for screening depression and assessing well-being across different populations and settings.