The present study is the first independent investigation of the Comprehensive Trail Making Test (CTMT; Reynolds, 2002) with both clinical and non-clinical samples. We examined convergent and divergent validity by exploring relationships between the CTMT and other measures. Discriminant validity was examined by comparing CTMT scores of non-clinical and clinical groups. Results indicate that the CTMT was largely unrelated to measures of processing speed and nonverbal reasoning, verbal processing, and psychiatric symptoms. The CTMT Composite score was able to differentiate between clinical and non-clinical groups with a large effect size. Overall, although further research is needed, results tentatively suggest that the CTMT may be a useful addition to a multifaceted neuropsychological test battery.