Molecular motor proteins comprise three protein superfamilies: kinesins, dyneins and myosins. Together, these proteins produce force for movement in an incredibly wide variety of cellular processes including vesicular transport, cell division, nuclear migration, muscle contraction, mechanochemical transduction, among others. In addition, molecular motors are expressed in both simple eukaryotes and in a tissue specific manner in higher cells. This methods volume explores the extreme functional and structural diversity of molecular motors and presents methods relevant to each motor family. In addition, it describes techniques directed at motors that fall outside of the 3 characterized families (i.e. dynamin and F1ATPase). This volume of the Methods in Molecular Biology series is an essential reference for cell biologists examining the function of motor proteins in a range of model organisms using both in vitro and in vivo techniques. This volume is a valuble source for biochemists and molecular biologists as well.