In Matthew's formula-citations, the Gospel author uses the verb πληρόω to denote the "fulfillment" of the OT fourteen times (1:22; 2:15, 17, 23; 4:14; 5:17; 8:17; 12:17; 13:14 [ἀναπληρόω], 35; 21:4; 26:54, 56; 27:9). Although not all the OT passages cited by Matthew were predictive in their original contexts, it has been widely assumed that since πληρόω can denote predictive fulfillment, Matthew had intended to use it as such in every instance. However, when Matthew's formula-citations are examined on their own terms, it becomes evident that πληρόω does not necessarily presuppose previous prediction. Rather, it appears to have been used in a wide variety of ways, with a broader semantic range than has previously been assumed. This study proposes that Matthew used πληρόω in regard to three distinct categories: five times in reference to non-predictive OT historical accounts (2:15, 17; 13:14, 35; 27:9), four times in reference to generally anticipatory OT themes (2:23; 5:17; 26:54, 56), and five times in reference to predictive OT prophecies (1:22; 4:14; 8:17; 12:17; 21:4). In view of this semantic range, it is proposed that in regard to the non-predictive and generally anticipatory passages, a more textually sensitive translation of πληρόω is "to climax," rather than "to fulfill." This study considers the validity of this translation in relation to the overarching theme of Matthew, as well as the individual uses of πληρόω in the formula-citation passages.