Few studies have considered the multitude of factors that influence learners’ accuracy of past tense-aspect use in
L2 Spanish. The present study fills this gap by examining course-level, task-modality, obligatory tense-aspect, and verb frequency
and regularity as predictors of English-dominant learners’ accuracy in contexts that require the Spanish preterit or imperfect.
Learner narrations from the COWS-L2H and CEDEL2 corpora were analyzed. Generalized mixed-effects models reveal that obligatory
tense-aspect and task-modality are significant predictors of accuracy and that frequency is only a significant predictor in
imperfect-obligatory contexts for students from the same Spanish program. Data from one Spanish program is interpreted as
providing partial support for the Default Past Tense Hypothesis (DPTH). The findings add complexity to our understanding of the
route of preterit-imperfect acquisition, showcasing plateauing effects and highlighting students’ use of the present as a default
form.