While in college students learn a great deal of new knowledge, and over time successful students learn to update their knowledge as new concepts, facts, and procedures are acquired. The metacognitive ability to accurately estimate one's knowledge was hypothesized to be related to academic achievement in college. The two studies, with a total of 254 undergraduates, reported in this paper examined the relationship between a measure of metacognitive word knowledge (the KMA) and performance in college. Using undergraduate GPA in a number of academic domains as criterion measures, this research provides support for the validity of the KMA as a predictor of success in college. Suggestions for further research relating performance on the KMA to learning in complex domains are offered. (PsycINFO Database Record (c) 2016 APA, all rights reserved)