Ground represents the greatest hazard to any construction project. It has been widely recognised by the UK geotechnical community that the proportion of project funding spent on, and time allowed for, investigating ground hazards is generally inadequate; the quality of some ground investigation is consequently poor.This Digest informs building and construction professionals who commission ground investigations, especially clients and their advisers who do not themselves have geotechnical qualifications and experience. It aims to raise awareness of the importance of ground investigation for routine projects and provides a summary of best practice. Tables give strengths and weaknesses of ground investigation techniques, with reference to British Standards and other relevant publications. 8 pages.