A psychotherapist's verbal interventions may be understood as promoting a client's eventual improvement by facilitating developmental change processes within the client. This approach is an alternative to the traditional search for statistical links between aggregates of therapist interventions and global outcome measures. Our approach employs models of clients' assimilation of problematic experiences within problem domains and therapists' implementation of theoretically specified aims. In an empirical illustration, one client's change within a particular problem domain and its links with therapist interventions were assessed qualitatively across the course of brief psychodynamic‐interpersonal treatmen