Mind wandering has often been studied in relation to psychopathology. However, debates remain as to whether sluggish cognitive tempo, recently termed cognitive disengagement syndrome (CDS), and ADHD symptoms could be unique predictors of mind wandering. Therefore, this study was aimed at documenting the associations between CDS, ADHD symptoms and mind wandering while controlling for age, sex, internalized symptoms, and sleep. A sample consisting of university students (N = 60; aged between 17 and 32 years; 65% female) completed measures of CDS, ADHD symptoms, internalized functioning and insomnia. Mind wandering was also assessed using the 5-item Mind Wandering Questionnaire (MWQ) and thought sampling during a reading task. Multiple regression analyses show that while younger age and inattention were significant predictors of greater levels of self-reported mind wandering on the MWQ, sex, CDS, hyperactivity/impulsivity, internalized symptoms, and sleep were not. In addition, no variables were able to significantly predict spontaneous and deliberate mind wandering as assessed by thought sampling. These findings raise important questions regarding the equivalence between measures of state-level and trait-level mind wandering. The associations between ADHD, CDS and mind wandering in young adults are still unclear, but our findings highlight critical methodological considerations for future studies that might further our understanding of the relationship between task-unrelated thought and psychopathology.