Objective: Most previous research on the antecedents of healthy food choice has not investigated the links between these antecedents and has focused on specific food choice rather than on an overall diet. In the present study, we tested the plausibility of an integrated theoretical model aiming to explain the role of different psychosocial factors in increasing the intention to adhere to the Mediterranean Diet (MeDiet). Design and Participants: A sample of 1940 Italian adults participated in an online survey that measured their attitude and perceived behavioral control (i.e., rational antecedents), subjective norm (i.e., social antecedent), positive and negative anticipated emotions (i.e., emotional antecedents), food choice health and mood motives (i.e., motivational antecedents), past adherence to the MeDiet (i.e., behavioral antecedent), and the intention to adhere to the MeDiet. Results: Structural Equation Modelling (SEM) analyses confirmed the plausibility of the proposed model. Perceived behavioral control was the strongest rational antecedent of intention, followed by the emotional (i.e., anticipated emotions) and the social (i.e., subjective norm) antecedents. Mediation analysis showed that motivational antecedents had only an indirect impact on intention via emotional antecedents. Finally, multigroup SEM analysis highlighted that past adherence to the MeDiet moderated the hypothesized paths among all the study variables. Conclusions: The above findings advance our comprehension of which antecedents public communication might leverage to promote an increase in the adherence to the MeDiet.