The structures and luminescent properties of a series of EU(2+) doped Ba and Sr berates have been investigated. From this study, a simple structural relationship is established that distinguishes violet and blue emitting compounds from those that emit at longer wavelengths (> 500 nm). In this model, emphasis is placed on the coordination environments of the O atoms. Berates containing O atoms highly coordinated by heavy alkaline-earth metal atoms produce longer wavelength Eu2+ emission.