Princess Elisabeth and Anne Conway were contemporaries whose lives present many striking parallels. From their early interest in Descartes’ philosophy to their encounter with Van Helmont and the Quakers in their maturity, both were brought into contact with the same sets of ideas and forms of spirituality at similar points in their lives. Despite their common interest in philosophy, and their many mutual acquaintances, it is difficult to ascertain what either knew about the other, and whether either knew anything about the other’s philosophy. This paper reviews the evidence for connections between them and their knowledge of one another. After outlining the parallels in their personal circumstances and the sources for their knowledge of each other, I discuss key intermediaries: Henry More, the Hartlib Circle, Francis Mercury van Helmont and the Quaker leaders Robert Barclay and George Keith. Although they were certainly aware of one another, the answer to the question of whether there was any philosophical inter-change between them remains especially elusive.