The paper discusses the public health significance of neuroticism, a personality trait characterized by a tendency to respond with negative emotions to threats, frustrations, or losses. Neuroticism is a robust correlate and predictor of various mental and physical disorders, comorbidity among them, and the frequency of mental and general health service use. The trait is associated with increased risk for mental disorders such as mood disorders, anxiety disorders, somatoform disorders, schizophrenia, and eating disorders, as well as physical health problems like cardiovascular disease, atopic eczema, asthma, and irritable bowel syndrome. Neuroticism also predicts shorter, less happy, less healthy, and less successful lives. The paper reviews genetic and environmental influences on neuroticism, including the role of specific genes like the serotonin transporter gene (5-HTTLPR) and its interaction with stressful life events. It also explores causal links between neuroticism and adverse outcomes, including overlapping genetic influences, neuroticism's role in experiencing stressful events and social support, and its impact on emotional reactivity to stress. The paper concludes by emphasizing the importance of understanding the nature and origins of neuroticism to develop effective prevention and treatment strategies.The paper discusses the public health significance of neuroticism, a personality trait characterized by a tendency to respond with negative emotions to threats, frustrations, or losses. Neuroticism is a robust correlate and predictor of various mental and physical disorders, comorbidity among them, and the frequency of mental and general health service use. The trait is associated with increased risk for mental disorders such as mood disorders, anxiety disorders, somatoform disorders, schizophrenia, and eating disorders, as well as physical health problems like cardiovascular disease, atopic eczema, asthma, and irritable bowel syndrome. Neuroticism also predicts shorter, less happy, less healthy, and less successful lives. The paper reviews genetic and environmental influences on neuroticism, including the role of specific genes like the serotonin transporter gene (5-HTTLPR) and its interaction with stressful life events. It also explores causal links between neuroticism and adverse outcomes, including overlapping genetic influences, neuroticism's role in experiencing stressful events and social support, and its impact on emotional reactivity to stress. The paper concludes by emphasizing the importance of understanding the nature and origins of neuroticism to develop effective prevention and treatment strategies.