This book is a collection of contributions to the field of constructive mathematics, which arose from a workshop held in 2003. The main idea of the workshop was to find a closer link between the practice of constructive mathematics and its foundations. The articles can be roughly divided into two main groups: foundations and practice, each of which has two further parts. The first subdivides into type theory and set theory and the second into analysis and topology. There is also an introductory chapter, where the contributions are reviewed from a more general perspective, and an introduction to the subject of constructive mathematics, together with basic references. Altogether there are 21 papers, which are fairly self-contained and which include a useful number of references and indications towards further reading.