Ah, I've always had a soft spot in my heart for heretics. Churches need a good heresy every century or so - keeps 'em on their toes. Here's what's said about Pelagianism in the Encarta Encyclopedia

Pelagianism, in Christian theology, a rationalistic and naturalistic heretical doctrine concerning grace and morals, which emphasizes human free will as the decisive element in human perfectibility and minimizes or denies the need for divine grace and redemption. The doctrine was formulated by the Romano-British monk Pelagius, a man of considerable learning and austere moral character. About 390 he went to Rome, where, appalled by the lax morals of Roman Christians, he preached Christian asceticism and recruited many followers. His strict moral teaching had particular success in southern Italy and Sicily and was preached openly there until the death (circa 455) of his foremost disciple, Julian of Eclanum.

You can find the entire article here (click). I've always thought of Pelagianism as a rather benign heresy.
-Joe Offer-