Abstract: In this paper a review of the constitutive models for unsaturated soils reported in the literature is brieflypresented first.The paper follows with a summary of some main aspects conceming the deformation behaviour forusaturated soils including expansive soils,loess and compacted soils,Batal on hardening plasticity theory and criticalstate concepts,the paper presents a general theoretical constitutive framework including several models for describingthe stress-strain behaviour of unsaturated soils.The framework is able to represent,in a consistent and unifiedmanner,many of the fundamental features of the behaviour of unsaturated soils,The results of laboratory tests on aclayey sand and a sandy clay are used to evaluate the ability of the models to reproduce,quantitatively,observedbehaviour The agreement between observed and computed results is considered satisfactory and confirms thepossibilities of reproducing the most imporiant features of unsaturated soil behaviour using a simple generalframework.