Introduction: the strange death of 'Arian' Milan; 1. Making distinctions: Christian identity and community in Late Antiquity; 2. A tale of two bishops: Auxentius of Milan and the election of Ambrose; 3. Framing the faith: Aquileia, De fide, and the rhetoric of unity; 4. Manufacturing consensus: communities, leaders and the first basilica crisis; 5. Popular appeal: unity and authority in the second basilica crisis; Conclusion: waiting for the Arians; Bibliography.