Before the Royal Society there was the Society of Astrologers, a group of around forty practitioners who met in London to enjoy lavish feasts, listen to sermons and exchange instruments and manuscripts. This article, drawing on untapped archival material, offers the first full account of this overlooked group. Convinced that astrology had been misunderstood by the professors who refused to teach it and the preachers who railed against it, the Society of Astrologers sought to democratize and legitimize their art. In (...) contrast to the received view of seventeenth-century London astrologers, which emphasizes their bitter interrelationships, this article draws attention instead to their endeavours to mount a united front in defence of astrology. The article locates the society's attempts to promote astrological literacy within broader contemporary programmes to encourage mathematical education. Unlike other mathematical arts, however, astrology's religious credibility was an area of serious concern. The society therefore commissioned the delivery and publication of apologetic sermons that justified astrology on the basis of its sacred history. In this context, the legitimacy of astrology was more a religious than a scientific question. The society's public relations campaign ultimately failed, however, and its members disbanded in the mid-1680s. Not only were they mounting a rearguard action, but also they built their campaign on out-of-date historical arguments. (shrink)