Over the last decade, translanguaging pedagogy has gained much traction in language education and has been taken up in a wide range of educational settings. Studies on translanguaging pedagogy, however, have largely focused on its affordances; research on its challenges remains limited. This classroom discourse study examines both the affordances and challenges of translanguaging pedagogy by analyzing the functions of translanguaging practices in one US superdiverse, multilingual secondary science classroom. Taking up the lens of criticality and superdiversity, we view classrooms as power-laden spaces and translanguaging as a social practice shaped by and shaping social norms and ideologies. Through discourse analyses of classroom interactions and interview data, we identified seven functions of classroom translanguaging practices. Our analysis shows that translanguaging offered students translingual support for accessing meaning and instruction and allowed the teacher to build relationships with students through translingual caring and translingual critical love. Students also engaged in translanguaging for translingual bonding and creating translingual safe houses. However, translanguaging was also used for translingual exclusion and translingual aggression. Our analysis sheds light on the complexity of translanguaging pedagogy. We call for (re)centering criticality in the research and practice of translanguaging pedagogy and developing students' critical language awareness in translanguaging classrooms.