Publisher Summary This chapter describes how to establish and maintain a Xenopus frog colony, how to obtain unfertilized eggs and prepare egg extracts, and how to isolate sperm chromatin as a source of template DNA. Xenopus egg extract has been extremely valuable for the analysis of numerous integral processes in cell biology including chromatin assembly nuclear assembly and nuclear protein import, DNA replication, and cell cycle control. One crucial feature of the Xenopus egg, and egg extract that makes it so useful for studying these processes is the stockpile of components that are required to support the rapid cell division cycles following fertilization. Extracts are prepared from unfertilized eggs. On fertilization, the egg is released from metaphase arrest and enters interphase, with the first mitotic cell cycle lasting approximately 90 min and the next 11 cycles lasting only 30 min each. The stockpile of components present within the egg not only supports these remarkably rapid embryonic cell cycles in vivo , but also supports the decondensation and remodeling of sperm chromatin, the assembly of remodeled chromatin into functional nuclei, and the replication of nuclear DNA in egg extracts, mimicking the events within the intact egg.