A positive developmental thrust becomes mobilized by virtue of therapeutic action. This thrust is specified in terms of a set of fundamental modes of development that are biologically prepared and have been identified through recent research. The modes are first apparent in infancy and continue throughout life. The setting conditions which allow for the fundamental modes of development to be reactivated are provided by the therapeutic relationship. It is hypothesized that the empathic availability of the therapist enables these modes to operate as powerful background influences. Developmental aspects of empathy and of availability highlight the importance of adult regulatory functions and the construction of shared meaning.