Book excerpt: An ever-growing roster of model organisms is a hallmark of 21st century Developmental Biology. Emerging model organisms are well suited to asking some fascinating and important questions that cannot be addressed using established model systems. And new methods are increasingly facilitating the adoption of new research organisms in laboratories. This volume is written by some of the scientists who have played pivotal roles in developing new models or in significantly advancing tools in emerging systems. - Presents some of the most interesting additions to the core set of model organisms - Contains contributions from people who have developed new model systems or advanced tools - Includes personal stories about how and why model systems were developed