How can I tell if a fund is a good performer?

You can't know how well it will perform in the future. If there were a foolproof way to know how well a given fund will do in the future, we could all retire at 30. But no one can know for sure.

But you can check out a fund's past performance relative to that of its peers. That is, if you're considering a small-cap fund, compare its performance to the average for all small-cap funds. Be sure to compare performance over the long term - at least three years and preferably five years. You can get a fund report with this information by punching in a mutual fund ticker into the quote box above. But even though a good track record might offer some insight into whether the fund is well-managed, you still can't be certain whether that past performance will continue.