This study examined a group of English as a New Language teacher candidates' (TCs') pedagogical knowledge (PK) of translanguaging in a teacher preparation course. We deep-dived into exploring how their translanguaging stance and design knowledge evolved over a course of a semester. Using a participatory research approach, data were collected through the TCs' weekly assignments, transcripts of final self-assessment videos, and field notes of all the course artifacts. Findings indicated that the TCs' translanguaging stance and design knowledge grew significantly. By the end of the semester, their translanguaging design knowledge was supported and guided by their stance. The TCs noted their PK of supporting emergent bilingual students expanded and transformed because of their understanding of translanguaging. The findings also showed that co-constructing knowledge with the professor and peers contributed a great deal to the TCs' PK growth. For these reasons, our study confirms that PK is dynamic and that advancing TCs' pedagogical practices requires teacher educators' intentional design of classroom activities and responsiveness to the learning process involving TCs. Widening the literature on translanguaging, we affirm that TCs can gradually expand their entire pedagogical repertoires through deepening their knowledge of translanguaging.