He was working as a session musician when an acquaintance read his birth chart to him. Amazed by how accurately it summed him up, Cainer went on to study with the Faculty of Astrological Studies. He was interested only in drawing up full horoscopes, based on people’s exact date, time and place of birth. Indeed, when first approached, back in 1984 to write a sun sign forecast column, he turned down the offer, opting instead to write books designed to help students learn the language of planetary symbolism. Cainer also co-designed one of the first astrological computer programs. In 1985 he wrote "Jonathan Cainer's Love Signs", and a cookbook, "The Junk Food Vegetarian".