The starting-point of this article is the fact that within the language of theology it is a widespread usage to identify public opinion with sensus fidelium. The Author is convinced that the two formulas cannot be directly superposed. An accurate examination of similarities and differences is necessary otherwise the undifferenciated use of the two locutions could bring elements of confusion and groundless conflict into the theological debate. As a matter of fact the difference does not only concern the difference of (...) field or disciplines - sociology for public opinion, theology for the sensus fidelium - so that it would be a matter of the same phenomena interpreted by different points of view. Even if similar dynamics in the two functions can be gathered, sensus fidelium and public opinion are of a different kind so that also subject, object, conditions and way of practice are different. On the basis of these differences the two dynamisms -both utterly important for the life of the Church - can be correctly applied in theology as well as in the more concrete praxis of the Church. (shrink)