In this chapter, we describe correlational research (focussing on confirmatory factor analysis, structural equation modelling, and multilevel modelling) through a construct validity lens, outline historical roots and developments in methodology that underpin modern measurement and correlational modelling, and summarise the types of knowledge that correlational approaches produce under a construct validation framework. The discussion introduces modern techniques that are geared to analyse correlational data most effectively, and examples are presented from three large-scale educational studies that are based on correlational data. The chapter concludes by describing some of the issues and debates relevant to correlational techniques and offer direction for other research methods and designs that can complement correlational construct validity approaches.