This volume is about the interpretive component of the grammar. It is about how the form of sentences relates to their informational contribution and to their conditions of use. Accordingly, the papers here try to pinpoint aspects of the meaning of sentences, to draw connections between these aspects of meaning and material present at syntactic structure, and to ask how we get one from the other. The papers here were written over the past five years. Interest in semantics coalesced and intensified during these years at MIT; we are especially happy to publish these papers now, in the first year of the new PhD program specializing in semantics.