Abstract: The Unpleasant and Pleasant Emotion Regulation Assessment (UPER-A) is the first self-administered scale that provides indicators of how individuals use their repertoire of emotion regulation (ER) strategies for both unpleasant and pleasant emotions as well as the perceived efficacy in ER. The UPER-A consists of a total of 27 items and 4 open-ended questions, divided into three parts: unpleasant ER strategies (Part I), pleasant ER strategies (Part II), and perceived efficacy in ER (Part III). The aim of the present study was to develop and do a preliminary validation of the UPER-A. A sample of 513 French adults (mean age = 30.7 years old, SD = 12.3, range= 17–72 years old; 63.9% female) completed the tool. UPER-A is composed of a battery of tools for Part I (9 items) and Part II (8 items), and also 2 sub-factors for Part III, and provides several scores: average frequency of strategy use, availability, predominant use, predominant type, unused strategies, perceived efficacy. Validity indicators (internal consistency, convergent validity, divergent validity, concurrent validity, and test-retest reliability) are satisfactory. This new tool permits us to take into account emotion polyregulation and to improve clinical orientations concerning unpleasant and pleasant ER difficulties. Further studies are needed to extend the validation of the UPER-A, in clinical populations or adverse contexts for example.