--- - |2 Abstract We tested a theory‐derived network of within‐person causal relations between experiential states in schema therapy of Cluster C personality problems. The sample consisted of 35 patients with panic disorder and/or agoraphobia and DSM‐IV Cluster C personality traits or disorders who participated in an inpatient programme. In a 6‐week schema therapy phase, the patients had nine or 10 individual sessions and completed measures of experiential states (anger, sadness, depression, anxiety, optimism, and schema belief) before and after each session. The impact of these six states on each other and on themselves over time was examined in mixed models. Schema belief was positively related to subsequent anger and sadness, whereas optimism was negatively related to subsequent schema belief, sadness, and depression. The results suggest that one could maximize the effect of schema therapy on dysphoric feelings in patients with Cluster C personality problems through a therapeutic focus on optimism and schema belief. - Clinical Psychology & Psychotherapy, EarlyView.