This book is a contribution to the study of morphological productivity, that is, the property of word-formation processes whereby new words are created to satisfy a naming need. It presents an up-to-date picture of this phenomenon, characterising its major attributes and addressing neighbouring theoretical concepts like availability, profitability or lexicalisation. Links are also established between those notions and N+N compounding, a word-formation process regarded as very productive but traditionally overlooked in studies of this type. Unlike other productivity surveys, mostly directed at affixation, a corpus of N+N compounds is here compiled to which the mainstream models of productivity are applied. This allows to detect the pros and cons of those proposals and to propose a model of productivity. Two measures, Indicator of Profitability (π) and Trend of Profitability (Π), are introduced which can be applied across word-formation processes and are able to compute their productivity based on semantic categories.