Habitat models address only 1 component of biodiversity but can be useful in addressing and managing single or multiple species and ecosystem functions, for projecting disturbance regimes, and in supporting decisions. I review categories and examples of habitat models, their utility for biodiversity conservation, and their roles in making conservation decisions. I suggest the use of influence diagrams in structuring causal webs and structural equation modeling to quantify relations, as a general framework for building models of habitat from which a known degree of inference can be made to biodiversity variables.