Résumé : This thesis focuses on the acquisition of emotional competence (EC) skills in adults and its impact on well being. The first part of the thesis is dedicated to the definition of EC, including a review of EC in order to better understand and operationalize its main dimensions and correlates. We also present a systematic review of EC intervention studies on adult populations in order to assess their outcomes and make recommendations for the development and implementation of future interventions. We then provide a theoretical and practical framework for emotional competence (EC) based interventions. We describe the main components of an EC intervention, underline the important characteristics of the intervention pedagogy and discuss theoretical and practical implications of this framework.In a second part we investigate whether a sustainable improvement in emotional competencies is possible in adults, and what are the conditions and effects of this improvement on well-being (e.g. on mental and physical health and quality of interpersonal relationships). Results of three empirical studies confirm that EC can be significantly increased following an intervention (and compared to a control group) and that this intervention impacts favourably personal and interpersonal well-being as measured by psychological health, quality of relationship and employability.A last part of the thesis explores the mechanisms underlying this improvement of competencies and well-being. We focus on emotional acceptance, self-compassion, self kindness and behavioural flexibility. Because there was no scale measuring self-compassion or self kindness in French, we validate two scales and assess the relationships between these constructs and well-being.We then examined the possible benefits of emotional acceptance and behavioural flexibility in a randomized controlled study, showing how increasing emotional competence can enhance these change processes and how these processes can, in turn, enhance well-being.This research helps to further elucidate the role of active change processes in EC increase related to the promotion of well-being.