This chapter examines Broughton’s engagements with early modern Jewish communities which, like the rest of his interactions, were fraught with polemic, tension, and controversy. It starts with Broughton’s excitement at receiving a letter from an Abraham Reuben of Constantinople, whom Broughton believed to be a learned and authoritative Rabbi; whom Broughton’s enemies believed to be a convenient fiction of his own making; and who was in fact a minor poet with no religious authority. Despite the rumours of its forgery, Reuben’s letter pushed Broughton into a spree of missionary activity, leading to the first Hebrew printings in Amsterdam (1605–1606), and a public debate with David Farar, a Portuguese converso physician who had settled in the Netherlands. Beyond the confusions and miscommunications of these events, this chapter examines the broader impact they had on Broughton’s scholarship. Specifically, it argues that Broughton’s obsession with Jewish conversion deeply informed the approach he took to theological controversy and scholarship, by orientating him towards unusually historical and philological methods that were radically stripped of doctrinal and dogmatic concerns.