The 3rd International Symposium on Nanotechnology in Construction (NICOM 3) follows the highly successful NICOM 1 (Paisley, UK 2003) and NICOM 2 (Bilbao, Spain 2005) Symposia. The NICOM3 symposium was held in Prague, Czech Republic from May 31 to June 2, 2009 under the auspices of the Czech Technical University in Prague. It was a cross-disciplinary event, bringing together RandD experts and users from different fields all with interest in nanotechnology and construction. The conference was aimed at: UL LIUnderstanding of internal structures of existing construction materials at nano-scale/LI LIModification at nano-scale of existing construction materials. /LI LIProduction and properties of nanoparticulate materials, nanotubes and novel polymers./LI LIModeling and simulation of nanostructures. /LI LIInstrumentation, techniques and metrology at nano-scale./LI LIHealth and safety issues and environmental impacts related to nanotechnology during research, manufacture and product use. Review of current legislation./LI LISocietal and commercial impacts of nanotechnology in construction, their predictions and analysis./LI/UL