In every language, many words can be used to describe how someone feels at a certain moment. Yet not everyone makes use of this rich emotion vocabulary in everyday life when talking about his or her feelings. Whereas some individuals tend to use specific and discrete emotion terms (e.g., "sad" or "frustrated") to describe an emotional experience, others tend to use broader terms (e.g., "bad" or "negative") that mainly communicate displeasure or pleasure. These individual differences have been called emotion differentiation (ED; Feldman Barrett, Gross, Christensen, & Benvenuto, 2001) or emotional granularity (e.g., Tugade, Fredrickson, & Feldman Barrett, 2004). According to these theoretical approaches, individuals with high ED are able to generate a distinctive, granular, and precise representation of their emotional experience, whereas individuals with low ED use terms that are located along a single dimension of pleasantness-unpleasantness (Feldman Barrett, 1998; Feldman Barrett et al., 2001). In the present article, we aim to present a novel method for assessing ED that more closely reflects this definition of the construct than other measures that have been previously proposed. Before we discuss how ED can be measured and present the rationale behind our novel method, we summarize theoretical considerations about ED's role in the emotion-regulation process and its relation to subjective well-being. These theoretical considerations will be relevant for deducting hypotheses on the predictive validity of methods assessing ED. The Functionality of Emotion Differentiation for Emotion Regulation and Well-Being As Kashdan, Feldman Barrett, and McKnight (2015) have argued, the use of specific, differentiated emotion words conveys important information about an emotion-eliciting event. According to this information, individuals who label their emotional experiences with specific terms can regulate their intense negative emotions more effectively, are better able to pursue personal strivings, and finally, are able to achieve greater well-being. These assumptions are in line with the feelings-as-information theory (Schwarz, 1990), which posits that people use emotions as a source of information about themselves or about their environment and 839138A SMXXX10.