The authors of this article, all of whom have been a part of this effort to assess argumentation in literacy-rich science curriculum, have struggled with our attempts to build 3 argument-related assessments—understanding, critiquing, and constructing arguments about scientific phenomena in both oral and written modes. Loosely affiliated with the Seeds of Science/Roots of Reading Project at Lawrence Hall of Science, this effort focused on creating a suite of assessments as models for how middle school science teachers might create their own school-based, curriculum-embedded assessments of science. After reviewing the broad scope and insights derived from a 10-year history of assessments that operate at the intersection of science and literacy, we zoom in on 3 vexing but informative challenges they encountered—and addressed (if not resolved)—as they tried to assess the comprehension, critique, and construction of oral and written arguments.