After a review of previous research, we explore a broader notion of sensitivity, where polarity is one of many facets, the others being connected with the nature of a given item. The discussion falls into two main parts. First we look at a cross-linguistic selection of temporal adverbials, and we study their distributions and interpretations with respect to factors such as aspectual variations and positive and negative contexts of occurrence. We analyse how the presence of negation in different parts of the sentence can cause variations in well-formedness or the temporal structure and breakdown/create cross-linguistic equivalence's within the group. The results of this cross-linguistic study also reveals the accidental negative polarity labelling of the English item and the stipulative status of licensing requirements. It appears that cases traditionally not covered by the label 'polarity sensitive' are expressions which are semantically close enough to fall into the same class, or that an item gets fragmented into parts belonging to different classes because of its articulated functioning. Despite the similarities, the Italian data, for instance, do not fit in the licensing/non-licensing partition defined on the English data. Then, we consider the English item any. In this case too, we detect a web of interactions, this time connected with its function as a quantifier and as an indefinite, as well as with positive and negative contexts of occurrence. Variations in reading are brought about by licensers, and we explore how the effect can be computed in a compositional way. They are also connected with the type of domain any quantifies over, a phenomenon common to indefinites in general, with specificity issues and with the type of statement in which any occurs. At the end of the thesis, we point to analogies between polarity sensitivity and other negation related phenomena such as negative concord marking.