Scholarship on the science of reading (SoR) has, in some instances, taken up more narrow views of reading in discussions and instantiations of reading assessment that do not center equity and justice, especially in schools. This can lead to less valid and even harmful reading assessment, especially for students from historically marginalized communities with diverse language, cultural, and neurological differences. Here, we draw on critically-minded reading research, as well as on work in equity-oriented educational assessment, to inform a justice-based reading assessment framework that can guide research, theory, policy, and practice. Using an equity-oriented and justice-based lens, the framework outlines three interwoven components: (1) relational and humanizing assessment practices; (2) justice-based products and outcomes; and, (3) a critical construct of reading. The framework compels designers, developers, and users to center the needs of rights-holders, and especially those from historically marginalized communities, throughout the assessment process. To do so, the framework outlines five principles that include orienting to equity and justice; prioritizing humanizing and critical assessment practices; grounding assessment in a complex, dynamic, and critical construct of reading for diverse populations; designing for justice-based social consequences, and engaging in critical debrief throughout. These principles guide eight phases of assessment, which we outline in detail. Finally, we discuss conceptual contributions as well as practical implications.