The predominant model of general personality structure is the Five-Factor Model (FFM), consisting of the five broad domains of neuroticism, extraversion, openness, agreeableness, and conscientiousness. A hypothesis of long-standing interest has been that personality disorders can be understood as extreme or maladaptive variants of the domains and facets of the FFM. The purpose of this article was to discuss the development and validation of FFM personality disorder scales. These scales assess the Section II personality disorders from the perspective of the FFM, as well as maladaptive variants of both poles of all five domains of the FFM.