This volume contains the proceedings of the 7th Asian Symposium on Progr- ming Languages and Systems (APLAS 2009) held in Seoul, Korea, December 14–16, 2009. The symposium was sponsored by the Asian Association for Fo- dation of Software (AAFS), Research on Software Analysis for Error-free C- puting (ROSAEC) Center of Seoul National University, and SIGPL of Korean Institute of Information Scientists and Engineers. Following our call for papers, 56 full submissions from 18 countries were - ceived.Eachpaper wasreviewedby at leastthree ProgramCommittee members with the help of external reviewers. The Program Committee meeting was c- ducted electronically over a period of two weeks in August 2009. As a result of active discussions, 21 papers (37.5%) were selected. I would like to thank all the members of the APLAS 2009 ProgramCommittee for the tremendous e?ort they put into their reviews and deliberations, and all the external reviewers for their invaluable contributions. The submission and review process was managed using the EasyChair system. In addition to the 21 contributed papers, the symposium also featured three invited talks by Koen Claessen (Chalmers University of Technology, Sweden), NaokiKobayashi(TohokuUniversity,Japan),andArmandoSolar-Lezama(M- sachusetts Institute of Technology, USA).