text: Shadow enhancers are groups of two or more enhancers that control the same target gene and drive overlapping spatiotemporal expression patterns. Shadow enhancers are found in a wide range of organisms, from insects to plants to mammals, particularly in association with developmental genes. While seemingly redundant, the individual enhancers of a shadow enhancer group have been shown to be critical for proper gene expression in the face of both environmental and genetic perturbations. Such perturbations may exacerbate fluctuations in upstream regulators.