Throughout development, complex structures such as organs and appendages form as directed by spatial and temporal cues. Studies have begun to define these cues, but we currently do not know how the various cues are integrated. Using the Drosophila wing imaginal disk, Guss et al. (see the Perspective by Affolter and Mann) examined the relation between the selector proteins and signaling factors that influence wing-specific genes. Wing development requires DNA binding by both selector proteins and signaling proteins for the specification of a developmental field.