Cytoplasmic dynein, which is the largest and arguably the most complex cytoskeletal motor protein, plays fundamental roles during cell division, nuclear positioning, and organelle and mRNA transport, by generating force and movement toward the minus ends of microtubules. Consequently, dynein is central to many physiological processes, and its dysfunction is implicated in human diseases. However, the molecular mechanism by which dynein produces force and movement remains poorly understood. Here, we describe the use of optical tweezers to probe the nanometer-scale motion and force generation of individual dynein molecules, and provide a hands-on protocol for how to purify cytoplasmic dynein from budding yeast in amounts sufficient for single-molecule studies.