The present paper will assume, for the purposes of argument at least, the essential validity of the claims made on behalf of Case Grammar, in particular that ‘the case notions comprise a set of universal … concepts which identify certain types of judgements human beings are capable of making about the events that are going on around them, judgements about such matters as who did it, who it happened to, and what got changed’ (Fillmore, 1968: 24). We shall investigate in some detail the practicability of Fillmore's statement that ‘we should take the “case uses” as basic and regard the observable “case forms” as derivable from them by the rules of the grammar’ (Fillmore, 1971: 36), by attempting to establish, informally, some of the rules that would be needed to generate certain correct surface forms in Classical and Vulgar Latin and, in so doing, we shall examine, taking into account both the traditional distinction between ‘grammatical’ and ‘concrete’ cases (in particular, as propounded by Kurylowicz, 1964) and aspects of the localist hypothesis, most recently fully discussed by Anderson (1971), the extent to which the changes attested in Latin and early Romance are merely surface re-structurings, and to what extent they are more profound. Finally, certain implications for the theory itself, as at present formulated, are presented and briefly discussed.