Proficiency is a key variable in late second language (L2) learning, but one that is undermeasured in current research. This study investigates whether L2 oral proficiency can be quickly and reliably assessed via the Spanish “elicited imitation task” (EIT; Ortega, Iwashita, Rabie, & Norris, 1999). Thirty-seven L2 learners of Spanish with varied L2 experience (from low to very advanced) were tested. The EIT’s external validity was assessed via correlation with the simulated oral proficiency interview. Further analyses examined the EIT’s internal reliability, discriminatory power, and usefulness in identifying subgroups (clusters) of learners within the sample. Results strongly support the utility of the Spanish EIT for measurement of oral proficiency in SLA research. Moreover, the availability of parallel EITs in other languages promises to facilitate comparisons across studies. Thus, more precise measurement and analysis of proficiency in SLA research is called for via standardized measurements including the EIT.