This chapter assesses current knowledge and develop recommendations about when one should use a selection index and what type should be used. Multiple trait selection can be facilitated through index selection, independent culling, or tandem selection. Evaluations of these three methods suggest that index selection is most effective in all cases, and decidedly more effective than independent culling or tandem selection in some cases. However, these evaluations all require that relative economic weights be known. In short-term selection programs, the assessment of relative importance of different traits is often compromised in recognition of the limited material in the breeding program. Formalized selection indices will not likely be useful for multiple trait selection in these types of breeding programs. However, index methodology could be used to great advantage in choosing parents for the plant breeding programs.