Background: We sought to test the hypothesis that methamphetamine use interferes with both the quantity and quality of one's education, such that the years of education obtained by methamphetamine dependent individuals serves to underestimate general cognitive functioning and overestimate the quality of academic learning. Methods: Thirty-six methamphetamine-dependent participants and 42 healthy comparison subjects completed cognitive tests and self-report measures in Los Angeles, California. An overall cognitive battery score was used to assess general cognition, and vocabulary knowledge was used as a proxy for the quality of academic learning. Linear regression procedures were used for analyses. Results: Supporting the hypothesis that methamphetamine use interferes with the quantity of education, we found that (a) earlier onset of methamphetamine use was associated with fewer years of education (p< .01); (b) using a normative model developed in healthy participants, methamphetamine-dependent participants had lower educational attainment than predicted from their demographics and performance on the cognitive battery score (p< .01); and (c) greater differences between methamphetamine-dependent participants' predicted and actual educational attainment were associated with an earlier onset of MA use (p≤ .01). Supporting the hypothesis that methamphetamine use interferes with the quality of education, years of education received prior to the onset of methamphetamine use was a better predictor of a proxy for academic learning, vocabulary knowledge, than was the total years of education obtained. Conclusion: Results support the hypothesis that methamphetamine use interferes with the quantity and quality of educational exposure, leading to under- and overestimation of cognitive function and academic learning, respectively. © 2011 .