Declarative languages build on sound theoretical bases to provide attractive frameworks for application development. These languages have been succe- fully applied to a wide variety of real-world situations including database m- agement, active networks, software engineering, and decision-support systems. New developments in theory and implementation expose fresh opportunities. At the same time, the application of declarative languages to novel problems raises numerous interesting research issues. These well-known questions include scalability, language extensions for application deployment, and programming environments. Thus, applications drive the progress in the theory and imp- mentation of declarative systems, and in turn bene?t from this progress. The International Symposium on Practical Applications of Declarative L- guages (PADL) provides a forum for researchers, practitioners, and implementors of declarative languages to exchange ideas on current and novel application - eas and on the requirements for e?ective use of declarative systems. The fourth PADL symposium was held in Portland, Oregon, on January 19 and 20, 2002.

Declarative languages build on sound theoretical bases to provide attractive frameworks for application development. These languages have been succe- fully applied to a wide variety of real-world situations including database m- agement, active networks, software engineering, and decision-support systems. New developments in theory and implementation expose fresh opportunities. At the same time, the application of declarative languages to novel problems raises numerous interesting research issues. These well-known questions include scalability, language extensions for application deployment, and programming environments. Thus, applications drive the progress in the theory and imp- mentation of declarative systems, and in turn bene?t from this progress. The International Symposium on Practical Applications of Declarative L- guages (PADL) provides a forum for researchers, practitioners, and implementors of declarative languages to exchange ideas on current and novel application - eas and on the requirements for e?ective use of declarative systems. The fourth PADL symposium was held in Portland, Oregon, on January 19 and 20, 2002.