The interpretation of in-situ geotechnical test data needs a unified approach so that soil parameters are evaluated in a consistent and complementary manner with laboratory results. A common thread in assessing in-situ tests is the focus on the geologic stress history, often expressed by the overconsolidation ratio (OCR). For clays, the OCR can be measured by consolidation tests on undisturbed samples, yet for sands is rather problematic to address. For 6 clays, a hybrid cavity expansion -critical state model is used to match responses measured CPT, CPTu, and DMT. Specifically, tip stress, sleeve friction, penetration porewater pressures, and flat dilatometer readings are fitted by parametric input of OCR, void ratio, friction angle, rigidity index, and compressibility parameters. The undrained shear strength (s u ) of clays is best handled via critical-state concepts. Discussions are included for pressuremeter, vane, and T-bar tests. For sands, select empirical methods derived from laboratory chamber testing on reconstituted clean quartz and siliceous sands are reviewed, specifically for effective friction angle φ , OCR, and K 0 . In a novel look, a special set of undisturbed (frozen) sand samples from 15 locations in Japan, Canada, Italy, Norway, and China is used to check interrelationships for the following in-situ penetration tests: SPT, CPT, and V s . Stiffness of all soils begins with the small-strain shear modulus (G 0 = G max = ρ T V 2 s ) that can be used together with strength (s u or φ ) to evaluate stiffness over a range of strains. Supplementary testing by PMT and/or DMT can provide intermediate stiffnesses for tuning of modulus reduction schemes, as well as independent assessments of K 0 and OCR.