The note serves as an introduction to a peer-reviewed set of papers which were inspired by and resulted from initiatives started at the workshop on soil aggregation in semi-arid and arid lands held in Las Cruces, NM on 8-10 May 1997. The two main objectives of the meeting were (1) to discuss and review soil aggregation processes in dry semi-natural areas and (2) to identify and evaluate methods for assessing soil aggregation in arid ecosystems.