Standards-based reforms in many Anglophone nations have been informed by "monoglossic language ideologies" that marginalize the dynamic bilingualism of emergent bilinguals. Recent developments in applied linguistics that advocate for "heteroglossic language ideologies" offer an alternative for standards-based reform. This article argues that standards-based reform initiatives will not be able to address the needs of emergent bilingual students unless they create "ideological spaces" that move away from monoglossic language ideologies toward heteroglossic language ideologies and "implementational spaces" that provide concrete tools for enacting this vision in the classroom. With a particular focus on the Common Core State Standards in the U.S. context, the article develops a vision for standards-based reform that begins to affirm and build on the dynamic bilingualism of emergent bilingual students. Specifically, the article explores two classrooms and the New York State Bilingual Common Core Initiative as starting points for theorizing how to develop ideological and implementational spaces that infuse heteroglossic language ideologies into standards-based reform initiatives while also emphasizing the role of monoglossic approaches to assessments in ultimately undermining the attempts that are currently being made.