This study investigates the relationship between impulsivity and the development of compulsive cocaine use in rats. The authors found that high reactivity to novelty predicts the propensity to initiate cocaine self-administration, while high impulsivity predicts the development of addiction-like behavior, including persistent or compulsive drug taking despite aversive outcomes. The study provides experimental evidence that a shift from impulsivity to compulsivity occurs during the development of addictive behavior, offering insights into the neural mechanisms underlying drug addiction. Specifically, high impulsivity rats showed higher addiction scores and greater resistance to punishment compared to low impulsivity rats, suggesting that impulsivity is a key behavioral marker for the vulnerability to progress to compulsive cocaine use. These findings highlight the importance of pre-existing impulsivity in the onset of compulsive drug use and emphasize the need to investigate the neurobiological mechanisms underlying this transition.This study investigates the relationship between impulsivity and the development of compulsive cocaine use in rats. The authors found that high reactivity to novelty predicts the propensity to initiate cocaine self-administration, while high impulsivity predicts the development of addiction-like behavior, including persistent or compulsive drug taking despite aversive outcomes. The study provides experimental evidence that a shift from impulsivity to compulsivity occurs during the development of addictive behavior, offering insights into the neural mechanisms underlying drug addiction. Specifically, high impulsivity rats showed higher addiction scores and greater resistance to punishment compared to low impulsivity rats, suggesting that impulsivity is a key behavioral marker for the vulnerability to progress to compulsive cocaine use. These findings highlight the importance of pre-existing impulsivity in the onset of compulsive drug use and emphasize the need to investigate the neurobiological mechanisms underlying this transition.