Recent approaches to multilingualism, such as translanguaging, emphasize the porous, fluid, and hybrid nature of language use. This article intends to show, through an example of a local language debating competition in Central Java, that culturally emblematic performances tend to create monolanguaging spaces, due to their monolingual focusing on certain language varieties that are iconic to local ethnolinguistic identity. Monolanguaging spaces are language ideological spaces in which speakers project an idealized performance of their ethnolinguistic identity. Ethnographic observation shows that the performance of monolanguaging spaces involves the erasure of speakers’ multilingual repertoires and translanguaging practices, in accordance to the language ideology surrounding the hegemonic prestigious language variety and in accordance to the local norms of status or power-based social interaction. Attending to monolanguaging spaces reveal it as a performance accomplished through discursive work and power relations, involving the misrecognition of its connection and dissonance to multilingual repertoires and practices. (Language ideology, erasure, translanguaging, monolanguaging space, performance, ethnolinguistic identity, Javanese)*