By combining the strength of previously described in vivo cell tracking methodologies, we have recently generated a set of transgenic zebrafish lines, called "PhOTO (photoconvertible optical tracking of…)" zebrafish. PhOTO zebrafish lines are suitable for cell tracking during highly dynamic events, including gastrulation, tissue regeneration, tumorigenesis, and cancer/disease progression. Global monitoring of cell shape, cell interactions, e.g., cell intercalations, coordinated division, and cell dynamics are accomplished by using fluorescence imaging of nuclear and plasma membrane fluorescent protein labeling. The irreversible green-to-red photoconversion property of Dendra2 fusions enables noninvasive, specific and high-contrast selection of targeted cells of interest, which greatly simplifies cell tracking and segmentation in time and space. Here we demonstrate photoconversion and in vivo cell tracking using PhOTO zebrafish.