This book introduces a new approach – Parametric Design Procedures (PDPs) – which combines the techniques of Design Procedures and Parametric Modeling to address the limitations of existing systems. PDPs use parameters (e.g. initial shapes, variables, operations, numbers and relationships) as inputs and calculate them through encapsulated mathematical processes to generate and explore solutions for the design problem being considered. PDPs provide a powerful and creative method to immediately compose a parameterized schema that can be used for design explorations. This offers possibilities to explore a particular design instance after a model is constrained through the generation of an infinite number of design instances which can be considered in the evolution of parametric design instances. The rational for, and features of PDPs are described. The viability of this approach is explored through a prototype implementation in Grasshopper. The brief for an architectural design competition is used as the basis for the prototype development. The implementation issues around PDPs are discussed and the paper concludes with recommendations for further research.