The limitations of Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT)'s embedded validity measures (EVMs) are well-documented, as estimates suggest up to 35% of invalid baseline performances go undetected. Few studies have examined standalone performance validity tests (PVT) as a supplement to ImPACT's EVMs. College athletes (n=1,213) were administered a preseason baseline assessment that included ImPACT and the Rey Dot Counting Test (DCT), a standalone PVT, among other measures. Sixty-nine athletes (5.69%) met criteria for suboptimal effort on either ImPACT or the DCT. The DCT detected more cases of suboptimal effort (n=50) than ImPACT (n=21). A χ2 test of independence detected significant disagreement between the two measures, as only two individuals produced suboptimal effort on both (χ2(2)=1.568, p=.210). Despite this disagreement, there were significant differences between the suboptimal effort DCT group and the adequate effort DCT group across all four ImPACT neurocognitive domains (U=19,225.000, p<.001; U=17,859.000, p<.001; U=13,854.000, p<.001; U=17,850.500, p<.001). The DCT appears to detect suboptimal effort otherwise undetected by ImPACT's EVMs.