This text introduces students to 22 different theories of development, comparing and contrasting them. A biographical introduction to each theorist is included, along with case studies and examples. The theorists covered range over both the developmental and the environmental traditions. For example, from the former, in the tradition of Rousseau, those covered include Gesell, Piaget and Montessori and from the latter, in the environmentalist/learning tradition, those covered include Mary Ainsworth, Bandura, Erikson and Chomsky.