This book provides a compelling argument for a radically modular view of the human language faculty. It does so on the basis of the most comprehensive study to date of how word formation is constrained by different components of the grammar. Peter Ackema and Ad Neeleman argue that complex words are generated by a dedicated rule system which interacts with the syntax on the one hand and the phonology on the other. Their detailed analysis of these interactions explains numerous observations, many of them new.