An area of ongoing debate among bilingual scholars and practitioners is the extent to which instructional languages should be separated in dual language bilingual education (DLBE). This article contributes to and extends this effort by proposing critical translanguaging space as a conceptual lens to guide the design of translanguaging pedagogies in DLBE programs. This concept is grounded in spatial understandings of languaging and learning and comprised of three interrelated dimensions: (1) dynamic languaging, (2) heteroglossic ideologies, and (3) critical consciousness. After outlining these central tenets, I concretize this approach through a case study of a researcher-practitioner collaboration aimed at fostering a dynamic languaging space in a DLBE classroom that had previously enforced strict language separation. Findings reveal the ways in which this project reflected the aims of a critical translanguaging space, including by affirming students' dynamic bilingual repertoires and identities, reframing linguistic expertise, fostering practice-based understandings of bilingualism, and creating opportunities for interrogating issues of equity. At the same time, the project fell short of cultivating students' critical consciousness, as critical inquiry was largely relegated to students' small group conversations. I conclude with a discussion of findings and implications for future efforts at fostering critical and flexible bilingual learning spaces.