This comprehensive work explores theories of economic growth through analysis of mathematical models. The authors construct and discuss several economic growth models, beginning with a one-sector model and progressing to a two-sector and finally multi-sector models with many capital goods. The economic basis and implications of the mathematical models are stressed. The authors place particular emphasis on subjects such as induced technological change; theorems regarding factor-augmenting technical change; reswitching of techniques and paradoxical behaviour in capital theory; price-quantity duality relations; and optimal economic growth.