The effort to understand the molecular biology of rotaviruses (RVs) has led to the development of procedures that can be used to study the replication and transcription of the RV genome, the assembly and structure of the rotavirion, and the structure and function of RV proteins. Because it is not possible to provide a detailed description of all the techniques developed, this chapter stresses only those that have broad application, or which represent important new technical advances. In particular, this chapter emphasizes procedures used to prepare large amounts of purified triple-(TLP), double-(DLP), and single-layered (core) RV particles; to synthesize viral RNAs in vitro, through the transcriptase and replicase activities associated with RV particles; to evaluate the RNA-binding activity of RV proteins; and to assemble core-like and virus-like particles (CLPs and VLPs, respectively) via the expression of RV recombinant proteins.