This book explores graded expressions of modality, a rich and underexplored source of insight into modal semantics. Studies on modal language to date have largely focussed on a small and non-representative subset of expressions, namely modal auxiliaries such as must, might, and ought. Here, Daniel Lassiter argues that we should expand the conversation to include gradable modals such as more likely than, quite possible, and very good. He provides an introduction to qualitative and degree semantics for graded meaning, using the Representational Theory of Measurement to expose the complementarity between these apparently opposed perspectives on gradation. The volume explores and expands the typology of scales among English adjectives and uses the result to shed light on the meanings of a variety of epistemic and deontic modals. It also demonstrates that modality is deeply intertwined with probability and expected value, connecting modal semantics with the cognitive science of uncertainty and choice.