This report drives a path through some of the main issues discussed by the 84 papers presented to the Session 1B – on Physical and Constitutive Modelling – of the 17th ICSMGE and evidences some of the results of major interest, with the aim of outlining the role of modelling in geotechnical engineering. Physical, theoretical/constitutive and numerical modelling strongly interact in design practice. Design is usually undertaken via simple conceptual models or rigorous numerical analyses; physical modelling provides important benchmarks for calibrate conceptual models and to validate numerical analyses and is particular useful when dealing with complex geotechnical problems.