This theory-building case study aimed to elaborate an account of anxiety and its treatment within an assimilation model of therapeutic change (e.g., Stiles, 2002). A team consisting of the senior author and two other co-investigators independently reviewed the case of Robert, a 52 year-old man who was successfully treated for generalized anxiety disorder (GAD) in a clinical trial of cognitive behavior therapy (CBT). The team observed the expression of Robert's major voicesthe assimilation model's name for the individual parts of a client's personality-in the audio record of the client's in-session dialogue. Prominent among these was a critic voice, described by co-investigators as harsh and derisive toward other aspects of the self. Our work led us to infer that, although the critic voice seemed closely associated with the anxiety that characterized Robert's GAD, it did not produce that anxiety directly through its attacks on his other voices. Rather, the critic voice induced vulnerability to specific, anxiety-arousing external circumstances by derogating Robert's coping skills or exaggerating the threat of specific external circumstances. Robert's anxiety then arose when he encountered those circumstances.