Response generative modeling (RGM) is an approach to psychological measurement which involves a "grammar" capable of assigning a psychometric description to every item in a universe of items and is also capable of generating all the items in that universe. The purpose of this chapter is to: 1) elaborate on the rationale behind RGM; 2) review its roots and how it relates to current thinking on validity; and 3) assess its feasibility in a wide variety of domains. The chapter concludes with a brief review of possible theoretical approaches to a psychologically sound approach to test construction and modelling. (54pp.)