In this paper it will be argued that the difference between existential and locative sentences is primarily structurally encoded at the v P/VP level (at the first phase of a derivation). The crucial question is which argument of the verb BE (the Location or the nominal argument (“Theme”)) is projected as the “external argument”, i.e., which argument is the subject of inner predication. In the case of existential sentences it is the Location argument which is the subject of inner predication, and in the case of locative sentences it is the nominal argument. The subject of inner predication becomes by default also the subject of outer predication, i.e., the topic of the sentence. Hence, in the case of locative sentences the nominal argument is the subject of outer predication, i.e., the topic of the sentence, and in the case of existential sentences it is the Location which becomes the topic. (Or, alternatively, the actual topic (the subject of outer predication) might be the situational/ event variable, and the Location functions as a restriction on it.) However, the actual arrangement of constituents in the sentences under discussion, as in any other Polish sentence, is determined by the pragmatic/communicative principles. Given this, it is reasonable to think that the NOM/GEN case alternation in negated existential/locative sentences is primarily a matter of syntax, and not one of information structure or scope of negation. The analysis will be modeled in accordance with the phasal model of Chomsky (2000 et seq.).