This paper reviews experiments done in the author's laboratory which led to the discovery of an Epstein-Barr virus (EBV) gene, BZLF1, whose product, ZEBRA, switches the virus from latency to the replicative phase of its life cycle. Recent experiments are summarized which explore the effects of EBV genome rearrangements and cell background on the expression of ZEBRA, and which investigate the viral targets of ZEBRA action.