This chapter and the next build on the foundation laid in the previous chapter by exploring the contribution that various forms of evidence can make toward supporting a conclusion regarding the meaning or interpretation of test scores. The issue of score meaning connects with the measurement section in that assumptions about the nature of measurement fit into the interpretation of test scores as outlined in this chapter. The issue also connects to the middle section of the book because in order to establish a causal assertion that a given construct causes a given set of test scores, one first needs to fix the reference of the terms used in the causal assertion. The present chapter develops a general theoretical framework. The next canvasses open questions related to the meaning of test scores. Chapter 11 will survey various types of evidence relevant to test validation research and explore how it bears on test score interpretations in light of the model and questions presented in this chapter.