Organoids are three-dimensional in-vitro-grown cell clusters with near-native microanatomy that arise from self-organizing mammalian pluripotent or adult stem cells. Although monolayer stem cell cultures were established more than 40 years ago, organoid technology has recently emerged as an essential tool for both fundamental and biomedical research. For developmental biologists, organoids provide powerful means for ex vivo modeling of tissue morphogenesis and organogenesis. Here we discuss how organoid cultures of the intestine and other tissues have been established and how they are utilized as an in vitro model system for stem cell research and developmental biology.