Mental disorder classification provides a definitional framework that underlies applied clinical and research efforts to understand, assess, predict, prevent and ameliorate the burden of psychopathology. Many classification frameworks exist, perhaps most notable being the ‘authoritative’ systems of the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders and the 11th revision of the International Classification of Diseases. However, numerous limitations of official classification systems have been identified, fostering the development of empirically derived, statistical and psychometric alternative classification approaches, which attempt to overcome those limitations. In this Review, we describe three such advances: transdiagnostic dimensional approaches (such as the Hierarchical Taxonomy of Psychopathology; HiTOP), network approaches and clinical staging approaches. We discuss their strengths, limitations, divergence, overlap, and scientific and clinical utility, with a focus on the potential synthesis and integration of disparate approaches towards better classification of mental disorders.