The National Geotechnical Properties Database contains information about site investigation reports, boreholes and samples. It contains geotechnical measurements taken over borehole intervals and on samples. Some of the data are obtained digitally from AGS files (Association of Geotechnical and Geoenvironmental Specialists - File Transfer Format), some are obtained manually from site investigation reports stored in the National Geoscience Data Centre (NGDC). The database currently contains geotechnical data from over 450 000 laboratory test samples and core descriptions, borehole observations and in-situ tests from over 96 000 boreholes extracted from over 4800 site investigation reports. The database underpins BGS geo-engineering properties and processes research and is an important information resource for answering enquiries and providing for the data needs of external customers. The distribution of data often follows major UK infrastructure developments and the coverage of BGS research, including UK rocks and soils engineering geology studies or the areas covered by ground information for sustainable development and geohazards projects. Much of the data are from site investigations for major trunk road construction schemes, often provided by Highways England (formerly the Highways Agency) and other major engineering projects. A small proportion of the data is from BGS laboratory test results. The final investigation data and information are supplied to BGS by clients, consultants and contractors either as final paper records or as Association of Geotechnical and Geoenvironmental Specialists (AGS) digital data transfer format files. AGS digital data transfer format files (.ags) are the preferred method of receiving data because they can be added to the database much more quickly and accurately than adding data by hand from paper records.