In this article, we introduce the term "vulnerability to achievement stressors," which refers to differentially low achievement when shifts in the educational environment "stress" or threaten the capacity of an individual or a group of individuals to make academic progress. We also introduce a methodological framework for assessing vulnerability to achievement stressors. Vulnerability to achievement stressors in students with learning disabilities (LD), relative to students without disabilities, is illustrated with two achievement stressors: (a) the shift in learning standards codified in Common Core State Standards, specifically the increase in complexity of the fourth-grade fractions curriculum, and (b) the COVID-19 pandemic, which decreased instructional structure by disrupting in-person teaching. Because these illustrations were embedded within randomized controlled trials, each with an inclusive instruction condition and an intensive intervention condition, they also provide the basis for concluding that intensive intervention is more effective than inclusive instruction for addressing students with LD's vulnerability to achievement stressors and for narrowing their persistently severe achievement gaps. [This is the online first version of an article published in "Journal of Learning Disabilities."]