Publisher Summary This chapter describes methods for preparing recombinant Elongin and ELL, and for assaying their activities in promoting rapid and efficient elongation by RNA polymerase II. Based on varied evidence from biochemical studies, Elongin and ELL appear to function similarly to increase the overall rate of transcript elongation by RNA polymerase II by a mechanism that involves suppression of transient pausing by polymerase at many sites along the DNA template. Both Elongin and ELL appear to suppress RNA polymerase II, pausing through direct interactions with polymerase by decreasing the time the enzyme spends in inactive conformations. Elongin and ELL can both stimulate the rate of elongation by purified RNA polymerase II in vitro. Two approaches for assaying Elongin and ELL transcription activities have proven successful. First, Elongin and ELL have both been shown to be capable of stimulating the rate of elongation by RNA polymerase II that has initiated transcription from a promoter in the presence of the general initiation factors TFIIB, TFIID, TFIIE, TFIIF, and TFIIH. Second, Elongin and ELL have both been shown to be capable of stimulating the rate of elongation by RNA polymerase II on oligo (dC)-tailed DNA templates in the absence of auxillary transcription factors.