The present study aimed to identify predictors of one aspect of sign language acquisition, sign learning, in hearing nonsigners. Candidate predictors were selected based on the theory that the observed relationship between phonological short-term memory and L2 lexical learning is due in part to common perceptual-motor processes. Hearing nonsigning adults completed a sign learning task, three assessments of short-term memory for movements (movement STM; two of which used sign-like stimuli), and two visuospatial STM tasks. The final sample included 103 adults, ranging between 18 and 33 years of age. All predictors were moderately to strongly correlated with the sign learning task and to each other. A series of regression analyses revealed that both movement and visuospatial STM uniquely contributed to the prediction of sign learning. These results suggest that perceptual-motor processes play a significant role in sign learning and raise questions about the role of phonological processing.