This book provides a research background for adults helping three to five year olds learn mathematics, including social and emotional processes as well as key mathematical ideas and common difficulties. It includes implications for practice and proposes presented with a playful and sensitive approach. It is illustrated with examples from the author's own research and work with practitioners. Following the introduction, the first chapter, Now We Are Teaching Three Year Olds Maths: Recent Changes to Early Years Mathematics, is presented. Section One, What Do We Know about How Young Children Learn Maths? A Holistic Approach, contains the following chapters: (2) Cognitive Processes; (3) Emotional Processes; (4) Social Processes; and (5) Physical Processes. Section Two, Implications for Practical Pedagogy, presents the second group of chapters: (6) What Do We Know about How Children Learn in Early Years Settings?; (7) What Does Teaching Mean with Very Young Children? and (8) Approaches to Planning and Assessment. Section Three, The Mathematics Curriculum: Appropriate Expectations and Common Difficulties, contains the final chapters: (9) Number; (10) Shape and Space; (11) Measures; and (12) Problem Solving. Following a conclusion, the last chapter of the book, Looking to the Future, is presented.