This book on star clusters addresses students as well as researchers i n astrophysics. It contains two pedagogically written surveys which ma ke the book well suited for class work. B. Carney presents our current knowledge of the relative and absolute ages of globular clusters and probes of the galaxy's chronology. He also studies their chemical hist ory and what they reveal about the complexity of stellar evolution. W. E. Harris studies globular cluster systems as subpopulations of one ga laxy's stars. He also addresses their role in deriving a mass profile for the Milky Way halo and what their luminosity distribution function tells us about the Hubble constant.