This study investigates the negative relationship between fluid and crystallised intelligence and Conscientiousness subfactors within the New Zealand workplace. Fluid and crystallised intelligence were assessed via the General Reasoning Test Battery 2 (GRT2; N = 1629). Two personality inventories were employed: The Fifteen-Factor Questionnaire (15FQ; N = 546), and the Occupational Personality Profile (OPP; N = 1083). 15FQ subfactors of Conscientious and Disciplined negatively correlated with fluid and crystallised intelligence. OPP subfactors of Detail-Conscious and Conformity also negatively correlated with fluid and crystallised intelligence. Subfactors for both personality measures correlated more strongly with crystallised than fluid intelligence. This finding is contrary to an earlier finding that Conscientiousness negatively correlates with fluid, but not crystallised intelligence (Moutafi, Furnham, & Paltiel, 2004). An explanation for this difference is discussed and the Intelligence Compensation Theory is introduced as an explanation for the observed relationships.