This paper describes how the taxation of virgin aggregates and the disposal of wastes in landfills is increasing the pressure for the use of novel, marginal and recycled materials in earthworks and engineered fills that form the foundations of transport infrastructure. Traditionally, an empirical recipe specification approach is used for the design and construction of these foundations. However, this approach, which closely controls allowable materials, does not consider the appropriate performance properties of these materials and restricts the use of marginal or recycled products. In addition, it does not fully exploit the properties of good quality or stabilized materials that may be used. Therefore, the United Kingdom (UK) Highways Agency is working towards the introduction of a performance specification for pavement foundations to replace the current empirical approach. This paper details the performance required of pavement foundations and materials, the philosophy of the performance specification that has been developed and addresses the issues associated with its implementation. It concludes that a two-stage implementation of the specification should be adopted and that the specification could be extended to any application that requires construction of a platform/foundation to support a pavement, such as industrial paving, railway track-bed or general fill.