It has been observed that in various languages the domain of direct ca
se assignment extends beyond the arguments of a predicate to include a
lso certain non-subcategorized phrases such as duration and frequency
adverbials. But to date no theory has been proposed to explain the ext
ension of the case domain or the particular limits of this extension a
ttested cross-linguistically. This paper offers such a theory, focusin
g primarily on Korean. Data from Korean, English, and other languages
are adduced as evidence for a universally available option whereby the
domain of direct case assignment is expanded to include a SITUATION D
ELIMITER, i.e., a (situation-quantifying) extensive measure expression
. It is further shown that certain thematic roles qualify as situation
delimiters because quantification is transferred to the clause from t
he nominal filling the role. The rule proposed for adverbial case is s
hown to correctly predict well-known semantic effects observed in tran
sitivity alternations which involve situation-delimiting roles, such a
s the locative alternation.