The feeling of emotional self-efficacy helps people understand how to handle positive and negative emotions. Emotion regulation indicates the process that helps modulate emotions, to adapt suitably to the demands of the environment. This study has a two-fold aim. Firstly, it analyses the relationships among emotion regulation; the personality traits of extraversion and emotional stability; and the feeling of efficacy of positive and negative emotions in an adolescent population. Secondly, it analyses the mediating role of personality traits (extraversion and emotional stability) in the relationship between emotion regulation and self-efficacy for positive and negative emotions. There were 703 adolescents who took part (49.9% male and 50.1% female) aged between 15 and 18 years (M=15.86, TD=0.30). The results observe the significant relationships among emotion regulation; the personality traits of extraversion and emotional stability; and self-efficacy for positive and negative emotions. The structural equation model confirms that the link between emotion regulation and self-efficacy is direct and is also mediated by the personality traits of extraversion and emotional stability. The study confirms that emotional self-efficacy beliefs are connected to the emotional regulation strategies used. Effective emotional regulation favours self-perception and emotional coping. There is a discussion about the results, which are connected to previous research.