The contribution of plant root systems to slope stability and soil erosion control has received a lot of attention in recent years. The plant root system is an intricate and adaptive object, and understanding the details of soil–root interaction is a difficult task. Although the morphology of a root system greatly influences its soil-fixing efficiency, limited architectural work has been done in the context of slope stabilization and erosion control, and hence it remains unknown exactly which characteristics are important. Many of the published research methods are tedious and time-consuming. This review deals with the underlying mechanisms of shallow slope stabilization and erosion control by roots, especially as determined by their architectural characteristics. The effect of soil properties as well as the relative importance of different root sizes and of woody versus non-woody species are briefly discussed. Empirically and intuitively, architectural features seem to determine the effect of root systems on erosion phenomena and an effort is therefore made here to link both aspects. Still, the research to underpin this relationship is poorly developed. A variety of methods are available for detailed root system architectural measurement and analysis. Although, generally time-consuming, a full 3D architectural description followed by analysis in software such as AMAPmod offers the possibility to extract relevant information on almost any root system architectural characteristic. Combining several methods of measurement and analysis in a complementary way may be a useful option, especially in a context of modelling.