Declarative languages have long promised the ability to rapidly create easily maintainable software for complex applications. The International Symposium of Practical Aspects of Declarative Languages (PADL) provides a yearly - rum for presenting results on the principles the implementations and especially the applications of declarative languages. The PADL symposium held January 19–20, 2009 in Savannah, Georgia was the 11th in this series. This year 48 papers were submitted from authors in 17 countries. The P- gram Committee performed outstandingly to ensure that each of these papers submitted to PADL 2009 was thoroughly reviewed by at least three referees in a short period of time. The resulting symposium presented a microcosm of how the current generation of declarative languages are being used to address real applications, along with on-going work on the languages themselves. The program also included two invited talks, “Inspecting and Preferring Abductive Models� by Luis Moniz Pereira and “Applying Declarative Languages to C- mercial Hardware Design� by Je? Lewis. Regular papers presented a variety of applications, including distributed applications over networks, network veri?- tion, user interfaces, visualization in astrophysics, nucleotide sequence analysis and planning under incomplete information. PADL 2009 also included ongoing work on the declarative languages themselves. Multi-threaded and concurrent Prolog implementation was addressed in several papers, as were innovations for tabling in Prolog and functional arraysin Haskell. Recent applications have also sparked papers on meta-predicates in Prolog and a module system for ACL2.