Introduction: Cognitive efforts tests, such as the Test of Memory Malingering (TOMM), are widely used internationally, yet emerging research suggests that performance on the TOMM can be affected by culture and education. This study examined the specificity of the TOMM and performance differences among Colombian adults, contrasting those with varying levels of literacy in order to evaluate the impact of these variables on error rates. It was hypothesized that literacy would be positively correlated with TOMM scores. Method: The sample consisted of 256 participants: the Absolute Illiterate participants had no formal education and no ability to read or write (n = 58), Functional Illiterate participants had no formal education and only basic reading and writing skills (n = 66), Literate participants had up to 12-years of education (n = 66), and Highly Literate participants had some post-secondary education (n = 66). Group differences for Trial 1 (T1) and Trial 2 (T2) were analyzed using ANOVAs and chi-square tests, along with post-hoc comparisons. Results: Mean T2 scores for the four groups were all above the suggested cutoff score of 45: the Highly Literate group had the highest mean score (49.3, range 41 to 50), and the Absolute Illiterate group had the lowest mean score (45.5, range 30 to 50). The Absolute and Functional Illiterate groups performed significantly worse on the TOMM trials than the literate participants. Cognitive performance as measured by indicators of verbal fluency and executive control significantly correlated with TOMM performance. However, when evaluated together in hierarchical logistic regressions, only age and literacy significantly predicted TOMM scores. Conclusions: Although the performance of Colombian adults suggests that the TOMM can be used cross-culturally with literate individuals, Colombian adults with poorer literacy skills performed significantly worse, raising concerns regarding the use of this measure with educationally-diverse samples. Research and clinical implications are discussed.