The Adult Personality section of the Psychodynamic Diagnostic Manual (2nd ed. [PDM-2]; Lingiardi & McWilliams, 2017) reflects the best effort of theorists, researchers, and clinicians to capture clinically relevant personality constellations, from healthy personality styles to highly troubled disorders. We specify some foundational assumptions impelling this work, especially as they differ from those underlying categorical, descriptive psychiatric taxonomies such as the DSM and ICD. We describe and give the rationale for changes from PDM-1 to PDM-2, call attention to ongoing controversies and our efforts to resolve or represent them in PDM-2, and note the importance of future research on personality.