It has been argued that the revised Minnesota Multiphasic Personality Inventory (MMPI-2) fails to measure the Big Five dimension of conscientiousness (C), an assertion supported by the research finding that none of the factors underlying the MMPI correlate substantially with the C factor of the NEO Personality Inventory (NEO-PI)-a popular operationalization of the Big Five model. In this study we reconsidered the relationship between the MMPI-2 item pool and the C factor of the NEO-PI-R (Form S). Collections of MMPI-2 C markers did not correlate much higher than .5 with the NEO-PI-R factor scale in cross-validation hold-out samples. Most pervasive, however, was the finding that MMPI-2 item markers of C were also strongly (in many cases, more highly) related to the NEO-PI-R factor of neuroticism (N). Efforts to purify collections of MMPI-2 C markers, first by careful item selection and then by suppression of N variance, were met with limited success. Intercorrelations among NEO-PI-R scales suggest that the difficulty in finding markers that discriminate between N and C extends beyond any shortcomings of the MMPI-2 item pool.