In his book, Neil Thin argues that if the society is to invest in social development, it is a must to be clear about the definition of this concept. It is essential to methodically link social progress to other dimensions of development. If this is not done, resources will continue to be wasted, and understanding, impaired. Thin rejects the concept of using the term ‘social’ to categorise all residual aspects of sustainable development that are not economic or environmental. Instead, he proposes an alternative classification using four key dimensions of social progress: social justice, solidarity, participation and security.