A Developmental approach to integrative psychobiology provides a flexible framework for both clinical assessment and treatment planning. Assessment of seven dimensions of personality using the Temperament and Character Inventory (TCI) allows for comprehensive description of individual differences in feelings, thoughts, and actions. Four temperament factors that are stable throughout life can be decomposed in terms of their underlying genetic structure. Character factors that mature in response to social learning can be decomposed in terms of the components that unfold in a stepwise fashion from infancy through adulthood. Pharmacotherapy and psychotherapy can be systematically matched to the personality structure and stage of character development of each individual. This provides comprehensive paradigm that integrates psychodynamic, cognitive-behavioral, interpersonal, and neurobiological insights into case formulation. Use of the TCI in clinical assessment and treatment planning was illustrated by a case independently assessed by Mardi Horowitz using another approach.