We describe the validation process of a case formulation protocol, based on the theoretical perspective of Behavior Analysis, in order to contribute to the development of a case formulation model aimed to organize the in-formation coming from evaluation, to reduce clinical judgment bias, and to orient the clinical intervention towards a coherent and consistent way with the analysis categories belonging to the field of Psychological Well-being. Validity was defined as a function of the use of a single case design with a time series methodology and the internal validity of the formulations, based on criteria of consistency among the categories and the descriptive and explicative hypotheses, and among these and the intervention plan. The clinical formulation process was finished with six cases, taking the intervention efficacy as the validity criterion. Results point to the high level of inference and hypotheses based on clinical judgment rather than on empirical evidences.