The present research investigated the effects of negation on young and older adults' comprehension of sentences. Participants read sentences, named probe words, answered comprehension questions, and completed the operation-span test. Negation adversely affected comprehension in both age groups such that probe word naming times were marginally slower and comprehension accuracy was reduced for negative sentences. Although older adults' comprehension overall was poorer than young adults, the negation effects were similar for both age groups. Furthermore, age was less predictive of negation comprehension than working memory. Unlike other variables that demonstrate age-related declines in reading comprehension, difficulties in processing negation may not increase with age. (Contains 3 tables and 1 figure.)