Book excerpt: Let [italic]a([italic]m, [italic]n) denote the [italic]mth coefficient of the [italic]nth cyclotomic polynomial [capital Greek]Phi[subscript italic]n([italic]z), and let [italic]a([italic]m) = max[subscript italic]n [conditional event/restriction/such that] |[italic]a([italic]m, [italic]n)[conditional event/restriction/such that] |. Our principal result is an asymptotic formula for log [italic]a([italic]m) that improves over a recent estimate of Montgomery and Vaughan.