The philosophers of antiquity had much to say about the place of friendship in the good life and its role in helping us live virtuously. Augustine is unusual in giving substantial attention to the dangers of friendship and its potential to serve as an obstacle (rather than an aid) to virtue. Despite the originality of Augustine's thought on this topic, this area of his thinking has received little attention. This paper shows how Augustine, especially in the early books of the Confessiones, carefully examines the potential of friendship to lead us astray. In particular, friendships may prove an impediment to virtue by: derailing our practical reasoning (rather than aiding it); fostering vices (rather than virtues); and misdirecting our love. Augustine's investigation of the murky depths of friendship shows an original philosopher and keen observer of the human condition at work.