Recent findings suggest that compromised patient effort occurs in nonlitigious settings, but the nature and base rate of suboptimal effort in these settings remains poorly understood. In the treatment-seeking, acquired brain injury, outpatient rehabilitation sample included in this investigation, 21.8% of the patients scored below recommended cutting scores for suboptimal effort on the Test of Memory Malingering (TOMM). Disability status was the only variable explored in this study to be associated with suboptimal effort. It should be noted, however, that the proportion of patients on disability was large in both the optimal and suboptimal effort groups, suggesting that failure on the TOMM may not be a specific predictor of disability status in this sample. Importantly, performance on the TOMM was unrelated to age, education, time from injury to evaluation, and injury severity. Depression and anxiety were also shown to be unrelated to TOMM performance in this rehabilitation sample. As expected, performance on neurocognitive testing was significantly lower in the suboptimal effort group. This study suggests that reduced effort occurs outside forensic settings, is related to neuropsychometric performance, and urges further research into effort across various settings.