Cyclin-dependent kinase (CDK) 7 was originally implicated in cell cycle control by virtue of its ability to phosphorylate and activate other CDKs. Subsequently, both CDK7 and its partner, cyclin H, were found to be associated with the general transcription factor TFIIH, suggesting additional roles for CDK7 in transcription and DNA repair. During the past year, a third subunit associated with CDK7 and cyclin H has been characterized, and the functional link between CDK7 and RNA polymerase II has been strengthened.