The book contains an introduction to the Lambda Calculus as the theoretical foundation of all 'Functional Programming' languages. The Lambda Calculus has been created by the American logician Alonzo Church in the 1930's and is documented in his works published in 1941 under the title 'The Calculi of Lambda Conversion'. Alonzo Church wanted to formulate a mathematical logical system and had no intent to create a programming language. The intrinsic relationship of his system to programming was discovered much later in a time in which programming of computers became an issue. The book 'A++ and the Lambda Calculus' also contains a brief introduction to the educational programming language A++, a minimal programming language that has been built with the Lambda Calculus as its foundation. The purpose of A++ is to serve as a learning instrument rather than as a programming language used to solve practical problems. A++ is supposed to be an excellent tool to become familiar with the core of programming and with programming patterns that can be applied in other languages needed to face the real world. A++ is presented in greater detail in the books: 'A++ The Smallest Programming Language in the World' (978-3-7469-3021-3) and in 'Programmieren lernen mit A++' (978-3-7469-3199-9).