This volume chronicles the proceedings of the Third International Symposium on Polyimides and Other High Temperature Polymers: Synthesis, Characterization, and Applications, held in Orlando, December 17-19, 2003. This volume is divided into three parts. Part 1. Synthesis, Properties and Bulk Characterization Part 2 Hybrids and Composites and Part 3 Applications and General Papers. The topics covered include: Synthesis, characterization and processing (including some novel approaches) of a variety of polyimides and other high temperature polymers; structure-property relationships; hybrids and nanocomposites using these materials and their characterization, properties and applications; segmental dynamics in polyimide materials; photoalignable polyimides; photoconductivity and photosensitivity of polyimides; ultrafiltration membranes from polyetherimide; polyimide as a tunneling barrier; polymer materials for nonlinear optical applications; alignment of SWNTs in rigid-rod polymer compositions; surface modification of polyimide; adhesion of Cu to polyimide surfaces; and polyimide erosion in a low Earth orbit space environment.