This quasi-experimental study investigates neuropsychological functioning differences between 63 active duty soldiers who were placed into three groups (MTBI, PTSD, control) to provide better information for differentiating PTSD and MTBI. The ANAM and MicroCog were utilized to measure psychomotor speed, memory, and attention. Participants with PTSD performed worse on most measures of psychomotor speed and attention, and endorsed more symptoms of depression and anxiety when compared to MTBI and control participants. Further, attention appears to be the best cognitive domain for differentiating PTSD from MTBI, whereas memory variables did not differentiate these groups. Clinical and research implications of these findings are discussed.