Objective: The goal of this investigation was to examine the predictive validity of Client Emotional Productivity (CEP), an operationalization of optimal client in-session emotional processing, possessing seven features: Attending, symbolization, congruence, acceptance, regulation, agency and differentiation. Method: CEP was related to improvement in depressive and general symptoms, in 74 clients (66% female, 34% male) who received experiential therapy of depression and this was compared to the relationship between client high expressed emotional (CHEEA) arousal and the working alliance (WAI) and outcome. Results: Hierarchical regression analyses revealed that working phase CEP predicted significant reduction of depressive and general symptoms over and above that predicted by beginning phase CEP, the working alliance and working phase CHEEA. Working phase CEP emerged as the sole, independent predictor of outcome for both depressive and general symptoms. Conclusion: Productive emotional processing, thus, mediates the relationship between the alliance and outcome and seems to go beyond mere activation and expression of emotional experience. It rather seems to involve an increase in the ability to process activated primary emotion in a productive manner specified by CEP.