The Social Stratification of Sundanese-Indonesian Phonetic InterferenceThis study is focused on Sundanese-Indonesian phonetic interference and their co-variation with social variables such as class, age, and using of Sundanese compared to Indonesian. The data was collected on two main styles, i.e., simple text reading and word list reading. The identifying of phonetic realization in respondent speech assisted by the CECIL software. To claim that interference is coming from Sundanese, neither from another languages, the study takes Weinreich's criteria of bilingualism that emphasize using of both languages in active interaction. In other word, the understanding without speaking bilingual treated as nonbilingual speaker. It is very important because there are too many speakers who are using Arabic in Islamic ritual but they never use Arabic in daily conversation. The selected respondent was Sundanese and Indonesian speaker only. The study find out that at least three of the social features have a strong correlation to the interference. The lowest interference level placed by the young speaker (second generation) with high education and with high frequency to speak in Indonesian than Sundanese. The middle position placed by the young speaker with lowest education level and speak in Sundanese more frequently than Indonesian. The other side placed by the first generation with at least middle education level. Between three main positions above spread the speakers with combination of social features, but the high to middle position dominated by the first generation and the middle to lowest level interference dominated by the second generation. This finding accepted by T-Student analysis on 95% significant degree.