Pho85 is a multifunctional cyclin-dependent kinase (Cdk) in Saccharomyces cerevisiae that has emerged as an important model for the role of Cdks in both cell cycle control and other processes. Pho85 was originally discovered as a regulator of phosphate metabolism but roles for Pho85 in glycogen biosynthesis, actin regulation and cell cycle progression have since been discovered. Ten genes encoding known or putative Pho85 cyclins (Pcls) have been identified and the Pcls appear to target Pho85 to specific cellular functions and substrates. In this chapter, we review the functions of the various Pcl-Pho85 complexes in budding yeast. We focus on the known biological roles of Pho85 with an emphasis on Pho85 substrates and cyclin-Cdk specificity.