This Element advances a novel view – the Epistemic Labour View – about the role, limits, and potential of the theoretical virtues as the arbiters of various versions of underdetermination. A central focus is to go beyond the often abstract discussions in this area and to show how the theoretical virtues can illuminate and resolve issues surrounding actual cases of underdetermination found in scientific practice. This title is also available as Open Access on Cambridge Core. This Element serves as the first work that systematically draws together both underdetermination and theoretical virtues.