The purpose of this guide is to provide a concise summary on in-situ testing and its application to geotechnical engineering. The aim of in-situ testing is to define soil stratigraphy and obtain measurements of soil response and geotechnical parameters. The common in-situ tests include: Standard Penetration Test (SPT), Cone Penetration Test (CPT), Flat Plate Dilatometer (DMT), Field Vane Test (FVT) and Pressuremeter Test (PMT). Each test applies different loading schemes to measure the corresponding soil response in an attempt to evaluate material characteristics such as strength and stiffness. Boreholes are required for the SPT and some versions of the PMT and FVT. For the CPT and DMT no boreholes are needed and the term ‘direct-push’ is often used. An advantage of direct-push technology is that no cuttings are generated. However, a disadvantage of the direct-push method is that hard cemented layers, bedrock, and some gravel layers can prevent further penetration. The guide has an emphasis on the Cone Penetration Test (CPT) and the Standard Penetration Test (SPT), since these are the most commonly used insitu tests in North America. The section on the CPT is a supplement to the book ‘CPT in Geotechnical Practice’ by Lunne, Robertson and Powell (1997) and is applicable primarily to data obtained using a standard electronic cone with a 60-degree apex angle and a diameter of either 35.7 mm or 43.7 mm (10 cm2 or 15 cm2 cross-sectional area). The section on the SPT is applicable to data obtained following ASTM standard D1586-99.