This book contains a series of papers selected from the peer-reviewing process for STAIRS-08: the fourth European Starting Artificial Intelligence Researcher Symposium, an international meeting intended for AI researchers from all countries, at the beginning of their career – PhD students or people holding a PhD for less than one year. STAIRS-08 is held in conjunction with ECAI, the European Conference on AI, and PAIS, the Prestigious Applications of Intelligent Systems. STAIRS is an opportunity for doctoral students and young post-doctoral AI fellows: an experience in submitting and presenting a paper to an international forum with a broad scope and a thorough selection process. It also represents an opportunity to gather knowledge and exchange ideas related to open research problems and novel approaches as well as to acquire information on European research careers and mobility. A total of forty papers were submitted from different countries. The areas of the submitted and accepted papers range from traditional AI areas to AI applications. Different topics are covered, such as Knowledge Representation, Machine Learning, Natural Language Processing, Planning and Scheduling, Multi-Agent Systems, as well as Semantic Web, Data Clustering for diversified applications, e-learning and Robotics.