The assignment of syntactic structure and its use to determine propositional aspects of sentence meaning requires the retention of information and computations on that information over short periods of time; i.e., it requires a working memory system. Experimental results in normal subjects and patients with various brain lesions indicate that measurements of working memory that are derived from commonly used tests of this function do not correlate with performance levels on tests of syntactic processing in sentence comprehension. In addition, concurrent verbal memory loads do not affect syntactic processing. These results lead to the conclusion that there is a specialization in the verbal working memory system for assigning the syntactic structure of a sentence and using that structure in determining sentence meaning that is separate from the working memory system that is measured by standard working memory tasks and that presumably supports other verbally mediated cognitive functions.