To improve habitat in a stream system, planning, implementing, and evaluating improvements must address the appropriate spatial and temporal scales, including (1) subbasin inventory information for all seasons of the year--a departure from the usual site or reach inventory normally done during summer, (2) a thorough analysis of factors limiting fish production in the subbasin during all seasons of the year, (3) identification of improvement techniques that address limiting factors, and (4) selection of sites for habitat projects in the basin. Items (1) and (2) are usually done by fishery biologists; items (3) and (4) are more interdisciplinary, thereby requiring skills of both biologists and hydraulic engineers. The evaluation of habitat projects encompasses physical, biological, and economic aspects that must be placed in an appropriate spatial and temporal context. This paper proposes a sequential process for planning and evaluating habitat improvement projects, and discusses examples from northwest Oregon and southeast Alaska.