Query Optimization and Simulation -- Selectivity Estimation of High Dimensional Window Queries via Clustering -- Spatio-temporal Histograms -- GAMMA: A Framework for Moving Object Simulation -- Advanced Query Processing I -- Medoid Queries in Large Spatial Databases -- The Islands Approach to Nearest Neighbor Querying in Spatial Networks -- Estimating the Overlapping Area of Polygon Join -- Spatial/Temporal Data Streams -- Density Estimation for Spatial Data Streams -- Change Detection in Time Series Data Using Wavelet Footprints -- Evaluation of a Dynamic Tree Structure for Indexing Query Regions on Streaming Geospatial Data -- Advanced Query Processing II -- The Optimal-Location Query -- Constrained Shortest Path Computation -- Accurate and Efficient Similarity Search on 3D Objects Using Point Sampling, Redundancy, and Proportionality -- Indexing Schemes and Structures -- Spatio-textual Indexing for Geographical Search on the Web -- Evaluation of Top-k OLAP Queries Using Aggregate R–Trees -- PA-Tree: A Parametric Indexing Scheme for Spatio-temporal Trajectories -- Novel Applications and Real Systems -- On Trip Planning Queries in Spatial Databases -- Capacity Constrained Routing Algorithms for Evacuation Planning: A Summary of Results -- High Performance Multimodal Networks -- Moving Objects and Mobile Environments -- Nearest Neighbor Search on Moving Object Trajectories -- Opportunistic Data Dissemination in Mobile Peer-to-Peer Networks -- On Discovering Moving Clusters in Spatio-temporal Data -- Advanced Query Processing III -- Semantic Caching for Multiresolution Spatial Query Processing in Mobile Environments -- Probabilistic Spatial Queries on Existentially Uncertain Data -- Topological Predicates Between Vague Spatial Objects.It is our great pleasure to introduce the papers of the proceedings of the 9th - ternational Symposium on Spatial and Temporal Databases – SSTD 2005. This year’s symposium continues the tradition of being the premier forum for the presentation of research results and experience reports on leading edge issues of spatialandtemporaldatabasesystems, including data models,systems,appli- tions and theory. The mission of the symposium is to share innovative solutions that ful?ll the needs of novel applications and heterogeneous environments and identify new directions for future research and development. SSTD 2005 gives researchers and practitioners a unique opportunity to share their perspectives with others interested in the various aspects of database systems for managing spatial and temporal data and for supporting their applications. A total of 77 papers were submitted this year from several countries. After a thorough review process, the program committee accepted 24 papers covering a variety of topics, including indexing techniques and query processing, mobile environments and moving objects, and spatial and temporal data streams. We are very pleased with the variety of the symposium’s topics, and we are proud of the resulting strong program.