This article describes TextEvaluator, a comprehensive text-analysis system designed to help teachers, textbook publishers, test developers, and literacy researchers select reading materials that are consistent with the text complexity goals outlined in the Common Core State Standards. Three particular aspects of the TextEvaluator measurement approach are highlighted: (1) attending to relevant reader and task considerations, (2) expanding construct coverage beyond the two dimensions of text variation traditionally assessed by readability metrics, and (3) addressing two potential threats to tool validity: genre bias and blueprint bias. We argue that systems that are attentive to these particular measurement issues may be more effective at helping users achieve a key goal of the new Standards: ensuring that students are challenged to read texts at steadily increasing complexity levels as they progress through school, so that all students acquire the advanced reading skills needed for success in college and careers.