Some students are less accurately measured by typical reading tests than other students. By asking teachers to identify students whose performance on state reading tests would likely underestimate their reading skills, this study sought to learn about characteristics of less accurately measured students while also evaluating how well teachers can make such judgments. Twenty students identified by eight teachers participated in structured interviews and completed brief assessments matched to characteristics their teachers said impeded the students' test performance. Researchers found information from evidence provided by teachers, teacher and student interviews, and student assessments that confirmed teacher judgments for some students and information that failed to confirm or was at odds with teacher judgments for other students. Along with observations about student characteristics that affect assessment accuracy, recommendations from the study include suggestions for working with teachers who are asked to make judgments about test accuracy and procedures for confirming teacher judgments. (Contains 3 tables.)