tBased upon the revised Job Demands and Resources Model (2008) we aim first, to test the relationsbetween work-family conflict and emotional exhaustion across time and second, to determine the roleof professional self-efficacy in this relation. A longitudinal study was conducted in two times, with ayear of interval in a Spanish Army sample (n = 242). To test the causal relations between work-familyand emotional exhaustion three models are tested: normal causal, reversed causal, and causal reciprocal.To test the role of professional self-efficacy in the relation between work-family conflict and emotionalexhaustion four alternative models are tested: independence, antecedent, mediation, and independenceplus antecedent models. Structural Equation Modeling results confirm the simultaneous reciprocal effectsmodel as it fits the data better than the normal causal or the reverse causal models. This result suggests aspiral process, where work-family conflict predicts emotional exhaustion and at the same time emotionalexhaustion increases work-family conflict. Likewise, this article contributes to clarifying the role of self-efficacy in the complex relationship between work-family conflict and emotional exhaustion.