Sediment transport in rivers provides a dynamic linkage between flow and channel form. Topics examined in this chapter include differences among wash load, suspended bed-material load, and bedload; entrainment of particles on the bed into motion and into suspension; flow competence; the influence of particle mixtures on entrainment relations; the major factors influencing concentration profiles of suspended sediment in river flows; mechanisms of bedload transport and approaches to the development of bedload and bed-material transport equations; and factors that complicate understanding and prediction of bed-material transport in rivers, including armoring, bedforms, modality, particle–particle interactions, spatial-temporal variability, turbulence, and the validity of transport threshold relations. The use of particle-tracing methods in combination with information on channel change to estimate bed-material transport is also presented.