Seismic inversion provides a description of a reservoir through the elastic properties. Conventionally, the elastic properties are then transformed into reservoir properties and possibly facies, in order to draw inferences from the volumes. Recently, an alternative approach has been made possible in which facies are jointly inverted with seismic. I will discuss the implications of this joint facies and impedance inversion, and how it changes the constraints we can apply to inversion. The new constraints offer a way for geophysicists to leverage their team’s geological and engineering knowledge in the characterization offered by seismic inversion, and I will show how that can produce useful results.