In recent years interactive visualization of 3D data has become important and widespread due to the requirements of several application areas. However, current user interfaces often lack adequate support for 3D interactions: 2D desktop systems are often limited in cases where natural interaction with 3D content is required, and 3D user interfaces consisting of stereoscopic projections and tracked input devices are rarely adopted by ordinary users. Touch interaction has received considerable attention for 2D interfaces, and more recently for 3D interfaces. Many touch devices now support multiple degrees of freedom input by capturing multiple 2D contact positions on the surface as well as varying levels of pressure and even depth. There is great potential for multi-touch interfaces to provide the traditionally difficult to achieve combination of natural 3D interaction without any instrumentation. When combined with a stereoscopic display as well as depth cameras, we believe that multi-touch technology can form the basis for a next generation of 3D user interfaces. Several research groups have begun to explore the potential, limitations, and challenges of this and other 3D touch environments, and first commercial systems are already available. The goal of the SIG "Touching the 3rd Dimension (T3D)" is to address the research and industrial challenges involved in exploring the space where the flat digital world of surface computing meets the physical, spatially complex, 3D space in which we live. The meeting will provide a common forum to attract groups of conference attendees who share their visions of the future and recent results in the area of improving 3D interaction and visualization by taking advantage of the strengths of advanced multi-touch computing.