Traditional approaches to psychopathology are based on a bivalent or binary view (healthy vs. ill), oftentimes obscuring an understanding of the heterogeneity of symptoms, fluctuations, comorbidities, and of relationships/boundaries between psychopathologies. The recent Research Domain Criteria (RDoC) approach recognizes these problems without providing mechanistic solutions. We propose a novel non-binary approach based on neurocognitive principles derived from the well-established, mechanistically transparent Metacontrol State Model of psychopathology (MSMp). We suggest (1) abandoning phenomenologically-derived classifications of psychopathologies altogether; (2) explaining functional and dysfunctional behavior by means of the same theory; and (3) reconstructing behavioral observations from basic mechanisms. In line with the ambitions of RDoC, our mechanistic account allows addressing, analyzing, and treating malfunctioning at its very core-the responsible mechanism, rather than focusing on observable symptoms that may not indicate a common problem. Our theory-guided, evidence-based approach has the potential to foster a novel mechanistic understanding of psychopathology, improve diagnostic criteria weighting, and make interventions more effective.