Natural soils and rocks are usually structured at various levels starting from the scale of the particles, pores and their networks up to the field scale. The particular structure in these materials, as often represented by the combination of fabric and bonding, may exist due to the occurrence of natural or induced external factors. The former are mostly related to sedimentation and diagenesis, while the latter mostly include anthropogenic processes. It is now well recognized that the effects of structure in geomaterials are of paramount significance when assessing their engineering properties. From the rheological point of view, these effects are similar for a great variety of geomaterials, including granular soils, clays and porous weak rocks. With the purpose of understanding and describing these effects, outstanding contributions have been made in the last two decades to both the experimental investigations and the constitutive modelling of structured geomaterials. These research efforts have helped in proposing a comprehensive and general behavioural framework for structured geomaterials. The "Geomechanics of structured materials" was the topic treated during a specific session of the annual ALERT Geomaterials Workshop held in Aussois (France) from the 8th to the 10th October 2007. A general overview of the behaviour of structured geomaterials and a timely state of the acquired knowledge in this field of geomechanics, as close as possible to the current state of practice, was offered. We are especially pleased to include in this Special Issue, hosted by Soils and Foundations International Journal, most of the contributions presented during the aforementioned ALERT Geomaterials workshop session. We are grateful to all the authors for having contributed with their works to the realisation of this Special Issue that we hope will constitute a useful source of information and inspiration.