I investigated the trajectory of processing variability, as measured by coefficient of variation (CV), using an intentional word learning experiment and reanalyzing published eye-tracking data of an incidental word learning study (Elgort et al., 2018). In the word learning experiment, native English speakers (N = 35) studied Swahili-English word pairs (k = 16) before performing 10 blocks of animacy judgment tasks. Results replicated the initial CV increase reported in Solovyeva and DeKeyser (2018) and, importantly, captured a roughly inverted U-shaped development in CV. In the reanalysis of eye-tracking data, I computed CVs based on reading times on the target and control words. Results did not reveal a similar inverted U-shaped development over time but suggested more stable processing of the high-frequency control words. Taken together, these results uncovered a fuller trajectory in CV development, differences in processing demands for different aspects of word knowledge, and the potential use of CV with eye-tracking research.