Anthropogenic landscape change has had a disproportionately large effect on temperate grassland systems. We used simulations of landscape change to compare the impacts of three commonly applied alternative residential development policies (protecting productive lands, growth boundaries, targeted protection of conservation lands) on ecological and socially important resources in a rural grassland landscape of northern Idaho, United States. Our simulations showed that development patterns were least socially acceptable and most detrimental to ecological resources under current land-use policies. Protecting productive agricultural lands led to the highest level of endangerment for remnant Palouse Prairie communities. Urban growth boundary policies produced the most socially acceptable development patterns and supported habitat for a wide range of species. Targeted conservation actions protected key habitat areas but did little to protect habitat for wide-ranging species. Detailed analyses such as these provide planners with the information required to assess and mitigate the consequences of policy decisions.