While taking foreign language classes or interacting in the target language community, language learners will be exposed to dialectal differences. This paper addresses how adult learners of Spanish in beginning, intermediate, and advanced Spanish courses at a large US university perceived a common sociolinguistic feature of Spanish, /s/-weakening, which can vary for stylistic, gender, and geographical reasons. The implications for teaching and learning foreign languages will be addressed, noting the importance of teaching common sociolinguistic features that are salient to native speakers but less salient to second language learners.