Prediction pervades L1 processing, but is unsteady in adult L2 processing. L2 prediction variability is associated to frequency, and L1 and L2 experience, and prior anticipatory experience via interpreting. However, these factors cannot explain variability at advanced L2 proficiency levels, and it is unclear whether interpreters are better predictors due to higher anticipatory experience or higher working memory (WM) capacity. We tease apart the effects of prior anticipatory experience and WM to explore additional explanations to advanced learners’variability making L2 predictions. Spanish monolinguals and English L2 learners of Spanish with and without interpreting experience completed a visual-world paradigm eye-tracking task and a number-letter sequencing working memory task. The eye-tracking task measured prediction of verbal morphology (present, past) based on suprasegmental cues (lexical stress: paroxytone, oxytone) and segmental cues (syllabic structure: CV, CVC). Results revealed that interpreters' use of cognitive resources during L2 prediction is closer to monolinguals than to non-interpreters. Also, with more lexical competitors, higher WM facilitates prediction in monolinguals and interpreter L2 learners, but hinders prediction in non-interpreter L2 learners. These findings indicate that prior anticipation experience and working memory modulate L2 prediction, and that attention to L1 and L2 morphology is cognitively demanding.