Selection targets multiple phenotypic traits simultaneously and results in evolutionary change that is governed by the pattern of genetic (co)variation that underlies these traits. Consequently, the genetic variance–covariance matrix (G), which summarizes the pattern of independent and shared genetic (co)variation across traits, is a central parameter in understanding multivariate evolution. Here we discuss the central role that G plays in understanding multivariate evolution.. We use an empirical example on life-history traits in the Indian meal moth (Plodia interpunctella) to illustrate how G can constrain phenotypic evolution. We conclude with some of the limitations of using G to understand multivariate phenotypic evolution.