Shortcomings ofapproaches to classifying psychopathology based on expert consensus have given rise to contemporary efforts to classify psycho- pathology quantitatively. In this paper, we review progress in achieving a quantitative and empirical classification ofpsychopathology. A substan- tial empirical literature indicates that psychopathology is generally more dimensional than categorical. When the discreteness versus continuityof psychopathology is treated as a research question, as opposed to being decided as a matter oftradition, the evidence clearly supports the hypothesis ofcontinuity. In addition, a related body ofliterature shows how psychopathology dimensions can be arranged in a hierarchy, ranging from very broad “spectrum level” dimensions, to specific and narrow clusters ofsymptoms. In this way, a quantitative approach solves the “problem ofco- morbidity” by explicitly modeling patterns of co-occurrence among signs and symptoms within a detailed and variegated hierarchy ofdimension- al concepts with direct clinical utility. Indeed, extensive evidence pertaining to the dimensional and hierarchical structure ofpsychopathology has led to the formation ofthe Hierarchical Taxonomy ofPsychopathology (HiTOP) Consortium. This is a group of70 investigators working together to study empirical classification ofpsychopathology. In this paper, we describe the aims and current foci ofthe HiTOP Consortium. These aims pertain to continued research on the empirical organization ofpsychopathology; the connection between personality and psychopathology; the utility ofempirically based psychopathology constructs in both research and the clinic; and the development ofnovel and comprehensive models and corresponding assessment instruments for psychopathology constructs derived from an empirical approach.