Despite widespread belief that passion is important for workplace success, research has failed to keep pace with theorizing in this domain, particularly as it pertains to measurement. The Dualistic Model of Passion, which is composed of harmonious passion (HP) and obsessive passion (OP), has been frequently adapted by management researchers. Two different versions of its measure, the Passion Scale, are concurrently in use. Therefore, we collected three samples of working adults (total N = 1497) to conduct a comprehensive psychometric evaluation and comparison of the 14-item and 12-item versions of the Passion Scale adapted to work. Despite sharing only five items, both versions demonstrated acceptable internal consistency and incremental validity over other work attitudes. However, the positive correlation between HP and OP is much smaller in magnitude in the 12-item version, which may account for the wide credibility interval reported by meta-analysis. Additionally, item response theory analysis revealed that neither version can assess very high or low levels of HP or OP, indicating that the Passion Scale may be best suited to measuring mid-range levels of passion. We leverage these conclusions to offer future research directions and best practices for passion research using this measure.