Development of the nematode Caenorhabditis elegans is highly reproducible, and the cell division patterns are virtually invariant. Transparency of the eggshell and cells enables the observation of intracellular events with a high temporal and spatial resolution. These unique features, along with the sophisticated genetic techniques, make this organism one of the most attractive model systems for dissecting regulatory mechanisms of dynamic cellular behaviors, such as mitosis, at an organismal level. In this chapter, we describe immunofluorescence and live imaging methods for analyzing mitotic spindle regulation. In particular, we present the use of double- or triple-labeled fluorescent strains for high-resolution two-dimensional and three-dimensional live imaging to analyze dynamic behaviors of mitotic spindles.