This paper represents the third installment of the Reading for Understanding (RfU) assessment framework. This paper builds upon the two prior installments (Sabatini & O'Reilly, 2013; Sabatini, O'Reilly, & Deane, 2013) by discussing the role of performance moderators in the test design and how scenario-based assessment can be used as a tool for assessment delivery. Performance moderators are characteristics of students that impact reading performance but are not considered a part of the reading construct. These include (a) background and prior knowledge, (b) metacognitive and self-regulatory strategies and behavior, (c) reading strategies, and (d) student motivation and engagement. In this paper, we argue there is added value in incorporating performance moderators into a reading test design. We characterize added value with respect to the validity of the claims derived from test scores, the interpretation of the test scores, and the relevance to instruction. As a second aim, we present a case for using scenario-based assessments and how they can be used to integrate into the test design both the performance moderators as well as other features that make the assessment more instructionally relevant.