After reviewing a rich set of evidence on the plausible nature of the U-shaped intergenerational trend in educational homophily and the negative trend in racial endogamy in the USA, let us turn to the challenge of quantifying intergenerational changes and cross-sectional variations in homophily. In this chapter, we review a comprehensive set of analytical tools put forward in the literature for studying the degree of sorting along the educational trait. To help navigate the colorful realm of the tools, we begin with introducing some classifications of the tools.