This paper discusses parametric design systems as a generative tool in architectural design. Parametric tools are algorithmically based, and therefore offer increased computational control over design geometry during design activity. Their adaptability and responsiveness to changing design criteria and requirements make parametric models especially useful for design exploration in complex and dynamic design settings. In performance based design, parametric control of form is particularly valuable, such that they allow the integration of performance analysis into design synthesis. However, parametric systems are often incorrectly mistaken as an emerging architectural style rather than a computational method, ascribing it a false skin-deep character that overshadows its true merits. Moreover, parametric models come with a price, posing limitations regarding representational flexibility and design complexity, which hinder effective design exploration. A critical awareness on both the potentials and limitations of parametric systems is therefore critical in their effective use during design.