Recent research has revealed new information about the Welsh Tudor mathematician, Robert Recorde who invented the equals sign (=) – what inspired his work and what was its influence on the development of mathematics education in the English-speaking world. The findings of that research, presented at a commemorative conference in 2008, form the core of this publication. The book begins with an account of Recorde’s life and an overview of his work in mathematics, medicine and cosmography. Individual chapters concentrate on each of his books in turn, taken chronologically, and are supplemented by chapters that present historical perspectives of Recorde’s work and its wider European links and one that sets Recorde’s work within the general knowledge economy.