The article by Edward R. Watkins reviews the research on repetitive thought (RT), highlighting its constructive and unconstructive consequences. Unconstructive consequences of RT include depression, anxiety, and physical health issues, while constructive consequences involve recovery from traumatic events, adaptive preparation, and improved mental health. The review identifies several principles that account for these distinct outcomes: the valence of thought content, the intrapersonal and situational context, and the level of construal (abstract vs. concrete processing). Among existing models, an elaborated version of control theory is proposed as the best framework to explain the diverse outcomes of RT. The article also discusses various forms of RT, such as depressive rumination, worry, perseverative cognition, and emotional processing, and their implications for mental health.The article by Edward R. Watkins reviews the research on repetitive thought (RT), highlighting its constructive and unconstructive consequences. Unconstructive consequences of RT include depression, anxiety, and physical health issues, while constructive consequences involve recovery from traumatic events, adaptive preparation, and improved mental health. The review identifies several principles that account for these distinct outcomes: the valence of thought content, the intrapersonal and situational context, and the level of construal (abstract vs. concrete processing). Among existing models, an elaborated version of control theory is proposed as the best framework to explain the diverse outcomes of RT. The article also discusses various forms of RT, such as depressive rumination, worry, perseverative cognition, and emotional processing, and their implications for mental health.