Foundations. The progression of impact fees -- National impact fee survey -- Legal principles of impact fees -- State impact fee enabling acts. Context. Proportionate-share basics -- Credits -- Impact fees and the planning connection -- Uniform measures of impact -- Variations of proportionate-share fee design. Applications. Proportionate-share fees for physical infrastructure -- Proportionate-share fees for social infrastructure -- Proportionate-share fees environmental mitigation fees for green infrastructure -- Proportionate-share fees for operations and maintenance. Implementation. Model proportionate-share development fee ordinance -- Development impact fee administrative code.