The need to understand the basicmechanisms of landslide behavior and other problems involved in the movement of soil mass in geotechnical engineering has been pushing forward the development of the knowledge of residual strength of soils. This chapter focuses on previous achievements related to the subject of the shear behavior of soils. In the first section, researches on the residual shear strength of fine-grained soils are reviewed. Following this is a detailed review of the shear behavior of soil mixtures composed of fine matrix and coarse fractions. From the point of view of the historical development of this research field, a comprehensive review of different aspects of past work is presented in an approximately chronological order within each section. In the last section of this chapter, main points emerging from previous researches are summarized by categorizing in accordance with main factors influencing shear behavior of soils.