Vertebrate development is best studied in an intact embryo model, but a robust interface between time-lapse microscopy and in vivo embryo health and maintenance can be difficult to achieve in model systems that rely on external factors for life support. This protocol presents a system for in ovo culture and time-lapse imaging of fluorescently labeled cells within living avian embryos, using a Teflon membrane that is oxygen-permeable and liquid-impermeable. The protocol describes the Teflon membrane assembly (the assembly size can be changed to fit smaller eggs, such as those of the quail), its interface with the egg window, and the use of an upright microscope and heated chamber. The use of the system is demonstrated in chick embryos by following individual fluorescently labeled neural crest cells, a multipotent stem cell-like population that differentiates into a wide range of derivatives and travels extensively throughout the embryo. By combining in ovo culture with confocal or two-photon four-dimensional time-lapse imaging, embryo health can be maintained for up to 5 d, and neural crest cell behaviors can be visualized for long periods of time (approximately 36 h). This technique has been adapted to study somitogenesis.