Essentially all forms of movement in the living world are powered by tiny machines called molecular motors. Some of these motors are soloists that can work alone and transport cellular constituents within the cytoplasm, others operate as a team with billions and billions of co-workers to power muscle contraction. However, the fundamental mechanism is the same: a miniscule structural change that results in a "step" of a few nanometers on a millisecond time scale. But what exactly is a "step"? What determines stepping velocity? How much force can be generated? And how is all that studied? Three classes of motor proteins (myosin, kinesin, dynein) are known to generate linear movement. One class of kinesins, termed kinesin-1, are dimers in which the two motor domains are coordinated in such a way that the motor can take several hundred steps in a hand-over-hand fashion along microtubules. Initial events in force generation involve the transmission of small structural changes triggered by ATP hydrolysis in the motor domain to adjacent domains that translate these initial events into a large conformational change. To study these structural changes, mutants of these motors are being generated and analyzed using cell biological, enzymatic, microscopic, two-hybrid, and single molecule assays. The results suggest a complex network of interactions that is dependent on key residues within the motor head and adjacent domains. We propose a novel mechanism for regulation of catalytic activity and dimerization.