Geomorphologists use information about sediment particles to characterize their physical and dynamic properties, and as a method for ascertaining their provenance. This article enumerates the indices used to describe the physical properties of individual particles and the most common methods that geomorphologists use to analyze and characterize assemblages of particles. The former include physical size, sedimentation diameter, and sieve diameter and the latter bulk sieve and instrumental methods of particle-size analysis. Some of the criteria that can be used to determine sample size and the methods used to characterize particle shape and mineralogy also are summarized, and the different theoretical treatments that can be used to describe natural particle-size distributions are discussed. The issues of how sediment properties, such as size and shape, are modified in transport and can be used to establish provenance are addressed in a companion article.