The eye–antennal disc of Drosophila is serving a guiding role in the studies of how eye identity is specified, as well as how the retina is patterned. However, this system also holds a great potential for studying the coordination between organ growth and specification when various distinct organs form from a common primordium. The eye–antennal disc gives origin not only to the compound eye but also to the head capsule, ocelli, maxillary palp, and antenna, and these organs develop bearing constant size proportions with each other. Here, we review recent results that have shed light on the mechanisms that control the specification and growth of organs of the eye–antennal disc and discuss how these controls are intertwined during the development of neighboring organs to ensure their constant shape and relative sizes. Developmental Dynamics 232:673–684, 2005. © 2005 Wiley-Liss, Inc.