As Wendy said, look at the FAQs, because we've done all this.With 401 K plans, there are often poor options, so you need to do what is possible. But in principle, if you have the option of CDs or individual bonds, you will do better than dollar cost averaging into a bond fund, if you are dollar cost averaging during a period when interest rates are lower than during the period when you are later withdrawing funds. This is because buying CDs or individual bonds lets you opt out of market values by holding to maturity. You cannot opt out with a bond fund. This is fundamentally different than stocks versus stock funds, because stocks do not mature, so you cannot opt out of market values.