Thinking about task-unrelated matters (mind wandering) is related to cognition and well-being. However, the relations between mind wandering and other psychological variables may depend on whether the former commence spontaneously or deliberately. The current two studies investigated the psychometric properties of the Spontaneous and Deliberate Mind Wandering Scales (SDMWS; Carriere, Seli, & Smilek, 2013). Study 1 evaluated the stability of the scales over 2 weeks (N = 284 at Time 1), whereas Study 2 (N = 323) evaluated their relations to Generalized anxiety disorder symptoms, Openness, Social desirability, and experience-sampling reports of intentional and unintentional mind wandering during an online cognitive task. The results indicated that the SDMWS were better fitted with a two-factor than a one-factor solution, although the fit was improved with the exclusion of one item. The scales exhibited strong measurement invariance across gender and time, and moderately high test-retest reliability. Spontaneous mind wandering predicted Generalized anxiety disorder and experience-sampling reports of unintentional mind wandering, whereas Deliberate mind wandering predicted Openness and experience-sampling reports of intentional mind wandering. Furthermore, Spontaneous mind wandering showed a negative association with social desirability of weak-to-medium strength. In sum, the scales generally showed favorable psychometric properties.