All the lifecycle series share the same goal of first growing and then preserving your portfolio, but they vary in their methods. Some track indexes and maintain a more or less static mix of assets. Most life-cycle offerings, however, invest more actively. Even Vanguard, which promotes a passive indexing strategy in its Lifestrategy brochure, invests 25% of each lifecycle portfolio in the actively managed Vanguard Asset Allocation VAAPX.

In the hands of the right manager, such active management can produce good results. But when an active manager concentrates in an asset class at the wrong time, tactical shifts can be deadly. If such maneuvers make you nervous, then a passive index approach might suit you better.