Politicians and districting commissions in counties, cities, and other local jurisdictions rely on demographic analysis and expertise to help draw local political boundaries and ensure their conformity with the law. In the 1990s, this process will occur in a context of exacting legal standards, which demand careful demographic measurement. One court ruling in particular ([Garza v. Los Angeles County Board of Supervisors]) cast a cloud of uncertainty around the fundamental guiding principle that each citizen's right to vote should be weighted equally with that of every other citizen in a jurisdiction. The application of those legal standards to demographically diverse settings will enlarge and expand potential roles for applied demographers. The authors review the basic rules governing the boundary-drawing process; illustrate their application in demographically complex settings (jurisdictions with a multiminority makeup and concentrations of noncitizens); and distinguish potential roles applied demographers can play at each of several stages in redistricting. Initially, local jurisdictions may need advice on measurement. Eventually, demographers may be called on to perform technical analyses to inform judicial review, as plaintiffs seek to identify and redress injustices and jurisdictions seek to defend themselves against legal challenge.