This volume contains a selection of papers presented at the 17th International Conference on Applications of Declarative Programming and Knowledge M- agement INAP 2007 and the 21st Workshop on Logic Programming WLP 2007, which were held jointly in Wu ]rzburg, Germany, during October 4-6, 2007. Declarative programming is anadvancedparadigmforthe modelingandso- ing of complex problems. This speci?cation method has become more and more attractiveoverthelastyears, e.g., inthedomainsofdatabases, fortheprocessing of natural language, for the modeling and processing of combinatorial problems, and...