The present study examined second language (L2) development in the perceptual identification of a dialectal sound of the target language, through an investigation of the role of individual learner experiences in L2 phonological development. A total of 213 English-speaking learners of Spanish across five levels of study and with varying dialect contact experiences completed an identification task, which tested perceptual categorization of Spanish dialectal aspirated-s (e.g., "siesta" ['si?eh-ta]). In accordance with postulates of L2 speech perception models (PAM-L2, SLM, L2LP), findings revealed influence of the first language phonology on categorization at early levels shifting toward nativelike, dialect-specific categorizations of aspirated-s for more experienced learners. Dialect contact factors of prior study abroad location, native speaker social contacts, and metalinguistic training were found to be predictors of the dialectal perceptual targets toward which the L2 learners developed--for those learners past intermediate-level language courses--highlighting how individual experiences shape L2 perceptual abilities.