Interest in the HEXACO Model of Personality has consistently grown in the past decade - with a particular focus on the newly proposed sixth basic factor: Honesty-Humility. In essence, this factor was proposed as the driving force behind cooperative, honest behavior and the basis for a modest, unassuming nature. However, whereas recent research has accumulated substantial evidence for the prediction that Honesty-Humility drives non-exploitative behavior, there is little conclusive evidence for the proposition that it also signals humility. We tested this conjecture in a web-based study - assessing modest behavior in terms of people's over- vs. under-representation of their actual abilities. As hypothesized, the Honesty-Humility factor scale and the Modesty facet scale of the HEXACO Personality Inventory-Revised predicted the degree to which participants' self-appraisals matched their actual general mental ability in the expected direction: those low in Honesty-Humility and/or Modesty overstated their ability.